can you help me fix this problem

when someone tries to register the following comes up,
Fatal error: Call to undefined function: uc() in /home/www/freebuxmoney.com/register.php on line 65
this is what is on line 65 of that file
$username = uc($username);
any ideas?
Answer #1
tell us more clearly
Answer #2
Do you have the uc function defined somewhere on the script?