Trimble sps720 rebotic total station and trimble yuma 2 tablet with Trimble access 2017 Radio connection problem.

Good afternoon everyone?ÿ

I am useing the trimble sps 720?ÿ rebotic total station with trimble yuma 2 tablet with trimble access 2017?ÿ when i am doing the layout near the stock piles its always say radio link down and when the total station setup on heigh elevation and i am doing the layout 4 to 5 feet low ground same connecting issue please let me know if any one have solution for this i really appreciate thanks.?ÿ