The actions you want to do are in your
vb styles admin page of the admin control panel of vbulletin.
You want to edit that style and correct the relative image paths to full urls so the images can be found.
You can also copy the prolenses folder from the forum to the gallery directory to see if that would help
See the issue is your using relative links to images therefore they are being looked for in your gallery directory instead of the forum hense the need to use full urls.