Drivers door occasionally won't unlock...

[Garrettcode]

I've got a 2008 Versa SL with keyless. Within the last 3 months I started noticing a problem where my drivers door won't unlock with the keyless entry fob. I push it once, the lights flash, and the door stays locked. Twice opens all the doors and flashes lights— but the drivers door is still locked, and I either have to pull the key out of the fob or a passenger has to reach over and manually unlock it.

Also, when this problem is at its worst, I can push lock and I'll hear all of the passenger doors lock (and a sound like the drivers door is trying to do something) and the alarm sounds, but the driver's door never actually locks, and you can open the door and set off the alarm.

I can get the problem to go away sometimes if I'm in the car and I use the power lock switch on the armrest a couple of times. It's like there's a calibration problem or something, because the problem isn't consistent.

The battery in the fob is probably old, so I'll try swapping it out, but at the same time all of the other doors are locking and unlocking, so I don't think power is the problem.

Thanks for your help guys!