pnCGI:IRC

First I had Problem with configuration the file index.php

ini_set("include_path",ini_get
("include_path").":http://popcorn-
vn.com/go/modules/pnCGIIRC");
...

But I only got Error "Fail to open file" there's no files or
directories in this path.
So I decided put all the files "config.inc.php" and
phpSniff.class.php in 1 dírectory with index.php
And It's OK
But now when I enter username & chat, this Error
appears: "Internal Server Error"

I don't know if I did something wrong. But please tell me
your ideas about my Problem.
Thanks