N500-450Mhz won't link up.

We have 2 devices 450 Mhz AP-EP setup as a wire replacement. Setup in are office they will link up with no antenna connected. After connecting antenna's to the radio they fail to link up or communications is lost between the 2 devices.

We have deployed 2 devices in the field about 9 miles of seperation that are encourting the same issue's with good siginal between the 2 sites. 

Has anyone else encountered the same problem ?

Thanks AL 

link could be too hot. Sweet spot of RSSI is about -55dBm--80dBm.