Not knowing which lock you have I (we) can only guess. Some of the older Bargman locks would need the inside knob tightened as they would vibrate loose over the years. Let us know what brand you have; pics are very helpful too.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7