Smart Key opens all doors except driver's

Is there an easy solution to the problem or do I go to my Toyota dealer for a warranty repair on my 2007 package 5 Prius?

After I successfully lock my car using the small button on the handle of any smart-key door, when I come back to my car and place my hand on the inside of the driver's door handle the car does not unlock. However, when I move to the back hatch and touch the sensing pad it does beep and unlock. Then I can return to the driver's door and it is unlocked.

It seems that the sensing pad on the driver's handle is out of action.

Is my diagnosis reasonable? Is there something else I should try?

 

Thanks, Ceric for helping me to narrow down the problem. Since we have 2 2007 Prii it was easy to compare them. On the good one the interior light turns on as it senses my approach. On the problem one the light remains off and the car cannot be unlocked by touching the sensing pad.

Thanks to you I can advise my dealer that the proximity sensor is the problem and not the sensing pad.

My fear is that the Canadian dealer sees so few Prii up here that they will not have anyone who can fix it. We'll soon see.