Index: global/library/Zend/Form/Element.php
===================================================================
--- global/library/Zend/Form/Element.php	(revision 3177)
+++ global/library/Zend/Form/Element.php	(working copy)
@@ -992,14 +992,12 @@
                 $loader->addPrefixPath($prefix, $path);
                 return $this;
             case null:
-                $prefix = rtrim($prefix, '_');
-                $path   = rtrim($path, DIRECTORY_SEPARATOR);
+                $prefix = rtrim($prefix, '_') . '_';
+                $path   = rtrim($path, DIRECTORY_SEPARATOR) . DIRECTORY_SEPARATOR;
                 foreach (array(self::DECORATOR, self::FILTER, self::VALIDATE) as $type) {
                     $cType        = ucfirst(strtolower($type));
-                    $pluginPath   = $path . DIRECTORY_SEPARATOR . $cType . DIRECTORY_SEPARATOR;
-                    $pluginPrefix = $prefix . '_' . $cType;
                     $loader       = $this->getPluginLoader($type);
-                    $loader->addPrefixPath($pluginPrefix, $pluginPath);
+                    $loader->addPrefixPath($prefix . $cType, $path . $cType . DIRECTORY_SEPARATOR);
                 }
                 return $this;
             default: