Imagick php windows

Imagick php windows

I am trying to use iMagick in Symfony2.
I am using PHP 5.4.16 and all i have done :
1-Copy php_imagick_nts.dll from php5-4 directory from the extracted
http://valokuva.org/~mikko/imagick-php54-php53.tgz to php/ext .
2-Rename it to php_imagick.dll and add the "extension=php_imagick.dll" to
php.ini
3-Create a page like this :
<?php
$a = new Imagick();
?>
but i receive this :
Fatal error: Class 'Imagick' not found in C:\xampp\htdocs\info.php
When I tried to use this in a symfony controller, the error occur again:
FatalErrorException: Error: Class 'Imagick' not found
Unfortunately the details about imagick extension not appear in output of
"phpinfo()"
Is this version is incompatible with PHP 5.4.16 ?! If yes,what version i
must use? Where? Thank for any help...