[MrNase]

Well, I finally managed it

Right now Iam using:

           			// Thumbnails
			if($foruminfo['forumid'] == '22') {
			
            $getpostids = $DB_site->query("SELECT postid from post WHERE threadid = $thread[threadid] LIMIT 1");
	 	    while ($getpostid = $DB_site->fetch_array($getpostids))
            {
	        $attachments = $DB_site->query("
			SELECT filename, attachmentid, IF(thumbnail_filesize > 0, 1, 0) AS hasthumbnail
			FROM " . TABLE_PREFIX . "attachment
			WHERE postid = $getpostid[postid]
	        ORDER BY rand() LIMIT 1
		    ");
		    
		    $attachment = $DB_site->fetch_array($attachments);
		    $attachmentid = $attachment['attachmentid'];
		    $hasthumbnail = $attachment['hasthumbnail'];
		    }
	        }
            // Thumbnails

for forumdisplay.php

but there's one little problem:
http://www.pagodentreff.de/diskussio...splay.php?f=22 displays must of the thumbnails correct but some of them only have this HTML code:
<img src="attachment.php?attachmentid=&amp;&stc=1&thumb =1" />

instead of

<img src="attachment.php?attachmentid=83&stc=1&thumb=1" />


How can that be!?
$attachmentid should be a number and not &amp; !?

Edit:
Some more information:
$hasthumbnail seems to be false for some reason.. But why? Those are normal thumbnails and the showthread.php displays them correct.