Greetings! 1999 GMC Yukon SLT 4 door. My electric door locks will work from the key fob but will not work from any button from inside. Will not work from the button by the rear doors. Put a new control panel on driver's side (all windows and locks). Still no good. The only way for me to lock doors is manually or key fob. Can anyone point at a starting point to sort this out? Thanks in advance.