If you applied the brakes after you engaged the LL, you probably hurt the LL. You must apply the brakes first, then engage the LL, while holding the brake pedal. After the LL is engaged, you can release the pedal. Ask me how I know. Happened with the first one I installed, last year.
It is actually a safety feature, so you will still have 4 wheel brakes, if you inadvertenly have the LL engaged.
