Not sure if it's electrical but need help po with my car's problem..

My car is Innova E and it's central lock/keyless entry was casa-installed when it was bought 2 yrs ago. Just recently, the door in the driver side is malfunctioning. If I press the lock button, every door will be locked except for that one. Same when I press the unlock button.

My workaround now is just to manually lock/unlock the door in the driver side, after pressing the lock/unlock. Need opinions from the kotse gurus, just in case there's a simple DIY to fix this. TIA.