Cisco Pix-501 VPN Connection problem

I have a Cisco Pix-501 and can remotely connect to the Pix but cannot Remote Desktop to any computer on the network. I cannot telnet into the Pix unless I telnet into the adtran we have on the network and then telnet back into the Pix. I can then make changes but I don’t know enough about the Pix to make the correct changes. Any ideas to resolve this would be great! Thanks.