WampServer

I am trying to get WAMP to work with the APC extension and am having difficulties getting it to work.

I have downloaded and placed the php_apc.dll file and placed in the the 'ext' directory. I see it listed in my list of available extensions and it is checked. However I get errors when trying to use the apc functions:

Fatal error: Call to undefined function apc_add() in C:\wamp\www\test.php on line 11

Here is a portion my php.ini file showing it listed and configured:

; Windows Extensions
; Note that ODBC support is built in, so no dll is needed for it.
; Note that many DLL files are located in the extensions/ (PHP 4) ext/ (PHP 5)
; extension folders as well as the separate PECL DLL download (PHP 5).
; Be sure to appropriately set the extension_dir directive.
;
;extension=php_bz2.dll
extension=php_curl.dll

...

;extension=php_xsl.dll
;extension=php_zip.dll

extension=php_apc.dll
;;;;;;;;;;;;;;;;;;;
; Module Settings ;
;;;;;;;;;;;;;;;;;;;

[APC]
apc.enabled = 1
apc.cache_by_default = 1
apc.enable_cli = 0
apc.shm_segments = 1
apc.shm_size = 64
apc.max_file_size = 1M
apc.stat=1

Any idea what I may have missed?