Lock Button - Door Handle

[LEXUS IS250 AWD]

Over the past few weeks there have been 3 separate times I exited the vehicle and hit the door lock button on the door handle, heard a long beep & the doors would not lock. I checked to make sure the gear was in park, that all the doors were properly closed and my lights were off (they're always on the automatic setting). Any idea why? <_<

Also, the doors would lock when I used the key fob.

[lenore]

You probably have a bad door lock actuator motor. It is starting to either get slow or not move all the way. That prevents the sensors from giving the locked position so that the alarm can actuate. When you did the key it moved the lock actuator into position...and allowed the alarm to engage.

[tex2670]

It also does that if the spare key is in the car.