Problem with a script

I installed pligg and it won’t work properly. It gives me an error:
Fatal error: Cannot redeclare _() in /home/iraszl/ on line 6

I identified the line is this:
function _($s) {return $s;}

I have a feeling Dreamhost servers can’t handle the _( in the code. Is this correct? How can I fix it? Am I missing the point entirely?