The Pro96 usually doesn't have desense or overload problems on 800 MHz. You may be too close to a tower that has the system you are trying to monitor and it may be overloading the Pro96 but I need more information on the system and how far you are from the tower. Since the 2006 only receives 800 MHz but doesn't trunk track, it's not a good comparison for what's happening with the Pro96. How well you receive the control channel determines how well you can trunk track and, if you are too close to a tower, you may be overloading the front end so it doesn't do a good job trunk tracking. Have you tried using the attenuator and seeing if that made any difference.