I recently added a new access point using direct connection. I installed SLMO cards on it. The Optipoint telephone sets are able to communicate within those connected directly to the AP but not to the other extensions connected directly on the HiPath 4000 main system. It says "Please try later" with a fast beep tone. I searched for this error and found out that it has something to do with the MLPP. After I configured it, the tone now sounds like a busy tone without the "Please try later" message from the Optipoint device. What else should I configure?