We have several links from ePMP 1000 series with 25dbi dish antenna and we use the last updated version of firmware 2.5.2 now. the distance is around 1 km.
it seems that all things are configured in two sites and SM could monitor the AP radio very good as followings, but they could not communicate and Error in Registration State is "Failed - SM Network Access:Retries exhausted".
Freq: 5055MHz, Channel: 20 MHz, RSSI: -60dbm, SNR:37 db
Do you mind showing us your AP configuration? Is anyone else connected to the AP? (Make sure to white out your MAC addressess if you post a screen shot)