Fatal error: Class 'imagick' not found

I am trying to install imagemagic php extension under WampServer 2.

• I've downloaded and installed ImageMagick . I've chosen ImageMagick-6.8.8-10-Q16-x86-dll.exe

• I've downloaded the php extension.

• I've moved the dll extension I just downloaded to C:\wamp\bin\php\php5.4.16\ext\

• I've altered php.ini (accessed it through wamp tray icon > right-click > PHP > php.ini) and added "extension=php_imagick.dll", without the quotes, to the extensions lists.

• I restarted Apache. Not noticing the extension displayed on the PHP extensions list from the tray icon, I restarted the wampserver. ImageMagick extensions now shows enabled on the list.

However, I cannot use it. Doing a quick test returns "Fatal error: Class 'Imagick' not found". In the phpinfo() shows only that the imagemagick has been added to env variables.

when I try to test the imagick :

$im = new imagick( 'test.jpg' );
// resize by 200 width and keep the ratio
$im->thumbnailImage( 200, 0);
 // write to disk
$im->writeImage( 'test_thumbnail.jpg' );

I get the error:Fatal error: Class 'imagick' not found What am I doing wrong? I'm working with win7 32 bit, phph 5-4-16 and apache2

The only way that I make it works is by using an older version of imagick:php_imagick-3.2.0b1-5.4-nts-vc9-x86.