Multiposter does not work on my site

[MyDarkTower]

I was wondering if anybody can help me. I can not post to my site with Multiposter 4 or 5. It works fine on other sites. All I ever get is the error:
"The remote server returned an error: (403) Forbidden"
Does anybody know what could be causing this? Could it be a mod that I am using? I listed below the only ones that I thought could interfer. Thank you for your time.

Site:Mydarktower.com/forum
Forum:Vbulletin 4.1.1 (Never worked on earlier versions either)
Possible Active Mods/Plugins:
Advanced Ip Ban Manager
No Proxy Allowed
Project HoneyPot

 

[CyberHacK]

Advanced IP Ban Manager is most likely causing it - Viewing the site now I see 500 ISE?

 

[MyDarkTower]

I disabled it and it still doesnt work.