Probably a simple problem but... I need help.

[Opserty]

I really doubt vBulletin would load your UserID into the $post['userid'], are you sure you not viewing a PM you sent to yourself or something? (Look at the variable vBulletin uses when it links your username to the profile. It uses $post['userid'], maybe if you tried moving the hook to postbit_display_complete and used $this->post['userid'] ?).

If it still doesn't work post the full code you are using.