I believe it should lock in the forward position, across the door. My 2010 2604SS has 2 doors and the handles on both will lock across the door. At a gas stop on the way to Big Band National Park in April I found the forward door was unlatched and was being held shut by the handle. Had it swung open in tight traffic it could have been bad. I check all doors and hitch at every stop now.
2010 Rockwood 2604SS
2008 Silverado 1500 LTZ 4X4
Great Wife and Idiot Yorkie
True Friends are like diamonds, precious and rare.
False ones like autumn leaves found everywhere