diff --git a/system/libraries/Form_validation.php b/system/libraries/Form_validation.php
index ebbf123..3c92852 100644
--- a/system/libraries/Form_validation.php
+++ b/system/libraries/Form_validation.php
@@ -230,7 +230,6 @@
 	{
 		$this->_error_prefix = $prefix;
 		$this->_error_suffix = $suffix;
-
 		return $this;
 	}
 
@@ -360,7 +359,7 @@
 				$this->set_rules($this->_config_rules);
 			}
 
-			// We're we able to set the rules correctly?
+			// Were we able to set the rules correctly?
 			if (count($this->_field_data) === 0)
 			{
 				log_message('debug', 'Unable to find validation rules');
@@ -377,7 +376,6 @@
 		{
 			// Fetch the data from the corresponding $_POST or validation array and cache it in the _field_data array.
 			// Depending on whether the field name is an array or a string will determine where we get it from.
-
 			if ($row['is_array'] === TRUE)
 			{
 				$this->_field_data[$field]['postdata'] = $this->_reduce_array($validation_array, $row['keys']);
@@ -392,7 +390,6 @@
 
 		// Did we end up with any errors?
 		$total_errors = count($this->_error_array);
-
 		if ($total_errors > 0)
 		{
 			$this->_safe_form_data = TRUE;
@@ -506,8 +503,6 @@
 			return;
 		}
 
-		// --------------------------------------------------------------------
-
 		// If the field is blank, but NOT required, no further tests are necessary
 		$callback = FALSE;
 		if ( ! in_array('required', $rules) && is_null($postdata))
@@ -524,8 +519,6 @@
 			}
 		}
 
-		// --------------------------------------------------------------------
-
 		// Isset Test. Typically this rule will only apply to checkboxes.
 		if (is_null($postdata) && $callback === FALSE)
 		{
@@ -587,11 +580,9 @@
 				$postdata = $this->_field_data[$row['field']]['postdata'];
 			}
 
-			// --------------------------------------------------------------------
-
 			// Is the rule a callback?
 			$callback = FALSE;
-			if (substr($rule, 0, 9) === 'callback_')
+			if (strpos($rule, 'callback_') === 0)
 			{
 				$rule = substr($rule, 9);
 				$callback = TRUE;
@@ -611,11 +602,14 @@
 			{
 				if ( ! method_exists($this->CI, $rule))
 				{
-					continue;
+					log_message('debug', 'Unable to find callback validation rule: '.$rule);
+					$result = FALSE;
 				}
-
-				// Run the function and grab the result
-				$result = $this->CI->$rule($postdata, $param);
+				else
+				{
+					// Run the function and grab the result
+					$result = $this->CI->$rule($postdata, $param);
+				}
 
 				// Re-assign the result to the master data array
 				if ($_in_array === TRUE)
@@ -639,7 +633,7 @@
 				// Users can use any native PHP function call that has one param.
 				if (function_exists($rule))
 				{
-					$result = $rule($postdata);
+					$result = ($param !== FALSE) ? $rule($postdata, $param) : $rule($postdata);
 
 					if ($_in_array === TRUE)
 					{
@@ -653,6 +647,7 @@
 				else
 				{
 					log_message('debug', 'Unable to find validation rule: '.$rule);
+					$result = FALSE;
 				}
 
 				continue;
@@ -721,7 +716,7 @@
 	{
 		// Do we need to translate the field name?
 		// We look for the prefix lang: to determine this
-		if (substr($fieldname, 0, 5) === 'lang:')
+		if (strpos($fieldname, 'lang:') === 0)
 		{
 			// Grab the variable
 			$line = substr($fieldname, 5);
@@ -785,7 +780,6 @@
 		}
 
 		$field = $this->_field_data[$field]['postdata'];
-
 		if (is_array($field))
 		{
 			if ( ! in_array($value, $field))
@@ -821,7 +815,6 @@
 		}
 
 		$field = $this->_field_data[$field]['postdata'];
-
 		if (is_array($field))
 		{
 			if ( ! in_array($value, $field))
@@ -829,12 +822,9 @@
 				return '';
 			}
 		}
-		else
+		elseif (($field == '' OR $value == '') OR ($field != $value))
 		{
-			if (($field == '' OR $value == '') OR ($field != $value))
-			{
-				return '';
-			}
+			return '';
 		}
 
 		return ' checked="checked"';
@@ -1099,19 +1089,6 @@
 	// --------------------------------------------------------------------
 
 	/**
-	 * Is Numeric
-	 *
-	 * @param	string
-	 * @return	bool
-	 */
-	public function is_numeric($str)
-	{
-		return is_numeric($str);
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Integer
 	 *
 	 * @param	string
@@ -1270,12 +1247,12 @@
 	 */
 	public function prep_url($str = '')
 	{
-		if ($str == 'http://' OR $str == '')
+		if ($str === 'http://' OR $str == '')
 		{
 			return '';
 		}
 
-		if (substr($str, 0, 7) !== 'http://' && substr($str, 0, 8) !== 'https://')
+		if (strpos($str, 'http://') !== 0 && strpos($str, 'https://') !== 0)
 		{
 			return 'http://'.$str;
 		}
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index fe0670a..9929cc3 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -101,7 +101,7 @@
 	 -  It now auto-increments quantity's instead of just resetting it, this is the default behaviour of large e-commerce sites.
 	 -  Product Name strictness can be disabled via the Cart Library by switching "$product_name_safe"
 	 -  Added function remove() to remove a cart item, updating with quantity of 0 seemed like a hack but has remained to retain compatability
-   -  Image manipulation library changes include:
+   -  :doc:`Image Manipulation library <libraries/image_lib>` changes include:
 	 -  The initialize() method now only sets existing class properties.
 	 -  Added support for 3-length hex color values for wm_font_color and wm_shadow_color properties, as well as validation for them.
 	 -  Class properties wm_font_color, wm_shadow_color and wm_use_drop_shadow are now protected, to avoid breaking the text_watermark() method
@@ -110,13 +110,17 @@
    -  Minor speed optimizations and method & property visibility declarations in the Calendar Library.
    -  Removed SHA1 function in the :doc:`Encryption Library <libraries/encryption>`.
    -  Added $config['csrf_regeneration'] to the CSRF protection in the :doc:`Security library <libraries/security>`, which makes token regeneration optional.
+   -  :doc:`Form Validation library <libraries/form_validation>` changes include:
+	 -  Added method error_array() to return all error messages as an array.
+	 -  Added method set_data() to set an alternative data array to be validated instead of the default $_POST.
+	 -  Added method reset_validation(), which resets internal validation variables in case of multiple validation routines.
+	 -  Added support for setting error delimiters in the config file via $config['error_prefix'] and $config['error_suffix'].
+	 -  _execute() now considers input data to be invalid if a specified rule is not found.
+	 -  Removed method is_numeric() as it exists as a native PHP function and _execute() will find and use that (the 'is_numeric' rule itself is deprecated since 1.6.1).
+	 -  Native PHP functions used as rules can now accept an additional parameter, other than the data itself.
+   -  Changed the :doc:`Session Library <libraries/sessions>` to select only one row when using database sessions.
    -  Added all_flashdata() method to session class. Returns an associative array of only flashdata.
    -  Allowed for setting table class defaults in a config file.
-   -  Form Validation library now allows setting of error delimiters in the config file via $config['error_prefix'] and $config['error_suffix'].
-   -  Added function error_array() to return all error messages as an array in the Form_validation class.
-   -  Added function set_data() to Form_validation library, which can be used in place of the default $_POST array.
-   -  Added function reset_validation() to form validation library, which resets internal validation variables in case of multiple validation routines.
-   -  Changed the Session library to select only one row when using database sessions.
    -  Added a Wincache driver to the `Caching Library <libraries/caching>`.
    -  Added dsn (delivery status notification) option to the :doc:`Email Library <libraries/email>`.
 
@@ -189,11 +193,12 @@
 -  Fixed a bug (#14) - create_database() method in the :doc:`Database Forge Library <database/forge>` didn't utilize the configured database character set.
 -  Fixed a bug (#1238) - delete_all() in the `Database Caching Library <database/caching>` used to delete .htaccess and index.html files, which is a potential security risk.
 -  Fixed a bug in :doc:`Trackback Library <libraries/trackback>` method validate_url() where it didn't actually do anything, due to input not being passed by reference.
+-  Fixed a bug (#11, #183, #863) - CI_Form_validation::_execute() silently continued to the next rule, if a rule method/function is not found.
 
 Version 2.1.1
 =============
 
-Release Date: Not Released
+Release Date: November 14, 2011
 
 -  General Changes
    -  Fixed support for docx, xlsx files in mimes.php.
diff --git a/user_guide_src/source/libraries/form_validation.rst b/user_guide_src/source/libraries/form_validation.rst
index 3e8855f..ef4be56 100644
--- a/user_guide_src/source/libraries/form_validation.rst
+++ b/user_guide_src/source/libraries/form_validation.rst
@@ -321,7 +321,7 @@
 function, which removes malicious data.
 
 **Any native PHP function that accepts one parameter can be used as a
-rule, like htmlspecialchars, trim, MD5, etc.**
+rule, like htmlspecialchars, trim, md5, etc.**
 
 .. note:: You will generally want to use the prepping functions
 	**after** the validation rules so if there is an error, the original
@@ -892,8 +892,9 @@
 
 		$this->form_validation->required($string);
 
-.. note:: You can also use any native PHP functions that permit one
-	parameter.
+.. note:: You can also use any native PHP functions that permit up
+	to two parameters, where at least one is required (to pass
+	the field data).
 
 ******************
 Prepping Reference