[Serusers] establishment call failure

hi, i am experiencing on little problem establishishing calls with my SER. First of all , i am running ser under linux opensuse, (ser version: 0.9.6 ) , i also installed rtpproxy and made the needed changes to my ser.cfg. When i "connetct" 2 different users with my SER locally , using softphone, everything looks fine. Gennerally the registration procedure using MySQL works fine(locally or not). When i am connected locally, a remote user can call me with no problems... The problem is the following, and i would appreciate if you could help me... When i try to call a remote user, the call cannot be established from my side. At the other side, the establishment of the call is ok. The message is the following: No ACK recieved... PS: I am only working now, till the level of the establishment of the calls... When i solve this problem , i will continue to the voice and video transmition, where i will need your help for sure... PS2: In order rtpproxy to run on the same computer with SER, i type rtpproxy with no parameters ?? can you help me with that too ??? Thank you in advance I send you also my ser.cfg