How can I use vBulletin's BBCode Parser/textarea outside of Forum?

[Oreamnos]

OK, I finally got the standard editor textarea. Actually, i was making that way harder than it was. Just forgot to include one of the JS files.

Next problem: When I use include('./includes/functions_bbcodeparse.php'); it makes a bunch of calls to undefined functions. The first one being :Fatal error: Call to undefined function: htmlspecialchars_uni() in /home/mysite/public_html/eslhq/esl_forums/includes/functions_bbcodeparse.php on line 336

Basically my code looks like this:

PHP Code:

include('../esl_forums/includes/functions_bbcodeparse.php');
echo parse_bbcode($_POST['message']); 


Can you help me get around this? Thanks