Found it. The else isn't the problem. The code I have in the text file is fine. The problem is that there is a javascript in the newreply, editpost, and newthread templates.
Remove this code from them (or something similar in each. I am only looking at newreply)
Code:
if (postmaxchars != 0) { message = "\nThe maximum permitted length is $postmaxchars characters."; }
else { message = ""; }
alert("Your message is "+theform.message.value.length+" characters long."+message);