What's causing my door lock not to function properly?
 

I purchased a new 2017 Silverado LT XC Z71. The dealer installed bed lights for the back bed. When I got home (189 miles from the dealer) I noticed the driver side push down button would not lock the other doors. The switch on the hand rest works, but not the push button. Dealer states they can not find nothing wrong and no codes to go on. Anybody got an idea as to why the locks are not working properly. Thanks, Paul