Not all trailers will lock the brakes. A flat bed will because of the low weight, especially empty.
In truth. you should NOT feel the trailer brakes come on in normal braking. The TV, and trailer should brake as one. You should only feel them when you use the manual lever. It should be a pretty good jerk depending on speed. Try it at 25, to 35 mph. You will have less jerk at higher speeds.
My TT brakes will not lock with the lever either. However. Ina HARD braking situation. I can hear the TT tire cry as they almost lock up.