Problem with php extension on windows

Dear

I have followed the installation notes for windows. I am runnin IIS8 with php version 5.3 and ADS 9.1 on windows server 2012 R2.

When I tried to connect to ads. I still received following message :

Fatal error: Call to undefined function ads_connect() in C:\inetpub\wwwroot\Didier\ads1.php on line 6

I checked the php.ini we found the extensions. But when I call the function it still recognize it.