$var

[sniped22]

$ph = "CheeseMan"
$usernam = substr($pokerhand, 9, $pos2-9);

$username ="Dealt to <font color='blue'>$usernam:</font>";
echo preg_replace($username1, $username, $ph);

 

produces:

Warning: preg_replace() [function.preg-replace]: Empty regular expression

 

Any ideas why?

[Wildbug]

Well, you haven't defined $username1 in the snippet of code you've provided.  If you haven't defined it elsewhere, then that's a good reason for it to be empty.