Well you selected vb3 integration when installing right? You get no errors at all? Does the login authenticate? You might want to post url's here so we can assist.
I would check cookies and license number
Set photopost and the forum to match cookies like so. You will need to edit your photopost cookie settings in phpmyadmin settings 171-173
cookie path /
cookie prefix bb
cookie domain .domain.com
Now your config-inc.php file must have the correct vb
license number entered on the $vblicense line. You can find this at the top of the vbulletin config.php file in the includes directory.