Mine doesn't either. It's a minor annoyance. The button's actually been used so much that it now actually has no 'F' in shift anymore =)

I've found that the shifter will work again (usually) if I twitch the ignition key once the car has started. The electrical portion of the ignition switch is a common problem with these cars, and a relatively easy DIY fix.

If that doesn't work, there is a shift lock microswitch in the console. I figure it's about a 2-hr job to repair - I had to remove my console to repair a snapped parking brake cable, and it's not a bad job either really.

See which is the culprit, and we can give you further instructions on how to fix!