Question : VPN concetrator

I'm trying to setup a cisco VPN concentrator 3000 I have configured it using the basic configuration and am now trying to test it. I'm using window 2003 enterprise server ( Active Directory) as the authentications server but each time I test it  I get "no response from server".

I'm using my interanl server IP addres as for my authentication. I have  tried using the default port and the prot of the server but get no response.

I have remote users who needd access  the network and this is a high priority
       

Answer : VPN concetrator

What protocols have you authorised on the Concentrator? IPSEC? L2TP? PPTP?
Is your user accessing over IPSEC or SSL VPN?
Not sure where you have put your concentrator; have you allowed the necessary traffic through your internal firewall for the Concentrator to talk to the authenticating service?