I experienced this too....here is what I discovered:
The two latches that lock the trailer when folded down are adjustable. You may have to turn thelittle nut to allow more height (length) so it can reach.
Check the nut on the long screw on the latch. That nut might not always stay in place when the camper is srt up and the latch is hanging down (see picture)
Or it could be you need to turn the little plastic tab on your door - make sure it is vertical, not horizontal when you set it down in the closed position...
Hope this helps?
2012 FR Flagstaff T12SDTH
1996 Shadowcruiser Pop Up Truck Camper
1967 Newell Motorcoach
2003 Ford F150 5.4 V8 Triton Super Cab
2004 Nissan Titan LE 5.6 V8 4x4 Crew Cab