We have a 15K mile 2003 Tahoe that just developed a strange power door lock problem. Both the key fob and driver's door main switch will UNLOCK ALL doors but will only lock front driver & passenger doors. The hatch & rear glass cannot be locked as there is no manual button or switch. Also the factory alarm system sees the hatch and rear glass as locked and will trigger the alarm if opened. At the same time the rear side doors, that do not lock remotely, do NOT trigger the alarm when opened!

Help anyone???