Call to undefined function mysqli_connect()

[slyan]

I really need help! I´v been trying to establish a connection between php, apache and mysql without succes. Apache is installed with php and it works. MySQL is also installed and working. When I try to establish contact through php I get the following error:

Call to undefined function mysqli_connect()

In the php.ini file I have enabled the extension php_mysqli.dll

Php version 5.2
Mysql 5.5
Apache 2.2

Code
$link = mysqli_connect('localhost','root', 'passw');

everything is spelled correctly etc

Anyone?