I have a VPN 3005 configured to authenticate against a Cisco Secure ACS 4 server and all user are connecting successfully via this method. I have installed an ACS 5.0 server and configured the relevant policies, defined the ACS server on the VPN 3005 and tested authentication (test is successfull). When I try to connect in via VPN the connection fails and in the logs on the VPN concentrator the new ACS server is going out of service - Server name = y.y.y.y, type = RADIUS, group = x, status = Not-in-service. It is associated with the correct group and the test authentication works, are there compatibility issues between the VPN 3005 and ACS 5.0? The VPN 3005 is running 4.7.2.P and the ACS is 184.108.40.206. Any ideas?