Howmany vpn group is supported on asa 5520 with remote access vpn configuraion.
1. If nat-control is disabled and you don't have any other NAT command in your config, you don't it. Try to remove the existing "NAT 0" command and "clear xlate".
2. You must make sure your inside network know that they can go through ASA to access remote vpn client IP. Do you have any layer 3 device behind ASA which is doing routing. If yes, please check it's routing table.