ENDIAN Firewall - Problem with RBL

I have just upgraded to version 2.3 and I seem to be having problems when I enable the RBL list under the SMTP Proxy. When I enable them I can refresh the page and it will turn then off again even after hitting save. If it doesnt do that and actually works the mail will stop sending and the queue will fill up rapidly. I have been using Endian for about 3 years now with the rbl enabled at about 10 different locations and has worked fine till I made the move to upgrade. I have also checked that we are not blacklisted anywhere. Am I missing something simple maybe? Any suggestions?