Try the following suggestions earlier posted. They are all related to RX diversity alarm.
Also possible cause for Rx diversity alarm is the mismatched / or losses on the RX received between the two diversities.
What equipment are u using? and what type of diversity if any(SPACE or Polarization)? Try to check if there is diversity on the site.
For Ericsson Network try to check the diversity if its AB. If then, try to set it to A only or to B only which ever good performance will be achieved for isolation purposes.