My CPE can not attach to the access point on my BTS.

I got to my client's site, I plugged my laptop to the POE of the radio; and was able to log into the radio (eForce 180). I observed that the radio was not attached to the Access Point (ePMP 2000) which it was connected. I tried attaching the radio back to the Access Point but could not. From the Home Interface of the radio it is showing “Operating Frequency: Scanning”. I increased the antenna gain of the radio and also decreased it as well, but the radio could not attach to Access Point.

Please can somebody tell me what to do in this case? Urgent reply will be appreciated.