Full doors or half doors? If full doors, I found out that I had put mine back together (replaced inner door handle assemblies) and had inadvertantly put the rods inside the window arm that lifts and lowers the windo. Didn't find out till I had it all back together and tried to open the window.
Make sure the arms are between the window arm and the inside panel of the door. Also check the coil spring on the latch assembly. Mine had slipped and was not holding the latches in the open position.
Hope this helps.