Messing with $post[message] in functions_newpost.php-The quest continues! Form vars?

[MTGDarkness]

When I try to put something into postbit_display_start, like, say

echo "this is a test statement";

What happens is, it gets put at the top of the page before the doctype declaration. I'm kind of stumbling around in the dark here.

--------------- Added [DATE]1235820573[/DATE] at [TIME]1235820573[/TIME] ---------------

Okay...
I wrote this plugin:

Postdata_start

if ($post[field11] && $post[field12])
{
require_once(DIR . '/includes/class_bbcode.php');
$parser =& new vB_BbCodeParser($vbulletin, fetch_tag_list());
$parsed_text = $parser->do_parse($text, $do_html, $do_smilies, $do_bbcode, $do_imgcode, $do_nl2br, $cachable);  

$text = $post[field11].$message.$post[field12];
}

And this in postbit_legacy:

<if condition="$post[field11] AND $post[field12]">$parsed_text
		<else />	$post[message]</if>

(replaces $post[message])

But when I tried it out, no HTML was outputted. And this is probably a serious security risk, seeing as people can type in PHP code for the fields and have it execute. How can I change that?