[SOLVED]rebuilding forum stats

[Fraxter]

I've a mistery problem.

I've created a new function file (includes/functions_foo.php) with the following content:

PHP Code:

function foo($input) {
//do something and get forumid etc.
build_forum_counters($forumid);
} 

Now i've created a second file in my forum root, called "foo.php":

PHP Code:

require_once('./includes/functions_user.php');
//do something
//call foo function
foo($input); 

Normally the foo function should rebuild the forum stats with the entered id. On my localhost test board it works fine!
I've installed the exact same files on my productive board on my server, and there it's not working. I've searched many hours, tested, changed etc. etc. but i can't find a solution.
Have anybody an idea what's the problem?

Thanks,

Pander23