My 2014 Volt has started to exhibit a strange problem when I attempt to unlock the car using the driver side button on the door handle. Prior to a few weeks ago I would just push the button in the morning and the door would unlock. Recently however, nothing happens when I push the button. I have to use the key fob to unlock the car first thing in the morning, but then the handle button works for the rest of the day. I have ruled out the handle button as causing the problem because I have tried the buttons on the other 3 doors and none unlock the car. Any ideas on what would be causing this problem?