The manual lever will apply brakes in proportion to how far you move the lever whether you are rolling or stopped.
While moving the controller will only apply the trailer brakes proportional to the force applied to the TV brakes. You should see an amperage reading displayed on the controller showing the amount of current going to the trailer brakes.
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles