Why isn't my template displaying?

[Cap'n Steve]

In newthread.php, I have this code:

if ($foruminfo['custom']) {
eval('$messagearea = "' . $temp['form'] . '";');
}

Then, in includes/functions_editor.php:

	if (!$foruminfo['custom']) {
		// create the message area template
		eval('$messagearea = "' . fetch_template($templatename) . '";');
	}

Basically, I'm trying to replace the standard editor with something else, but not only does it not show up, all I get is a blank page. Any help would be appreciated.