mate I have EXACTLY the same problem..they worked intermittantly...and then oneday jsut stopped:(
Im not sure whats wrong at all.....Im glad someone else has it.....it really pis*es me off.maybe we can knock our heads together??
i bought a replacement panel with bulbs (for a non-se) model and it didnt work......and my door buttons work perfectly as my actual red door lights work on and off with the door opening an dclosing...maybe its something to do with the wiring or bad earth??

Did this problem ever get resolved?

I have something similar going on....

- open the door
-unscrew the sensor housing
-pull the sensor out and disconnect

do this with both doors.

also under the bonnet dusconnect the sensor.

then replace the sensors individually and press/release the button afew times.

this should allow you to see if it is an individual sensor that is knackered or whether it is something else. mine was the bonnet sensor bracket not being high enough to fully close the button

I had a look at mine today - the drivers side switch is working perfectly, however the passenger side isn't working at all.

I put a voltmeter across the terminals off the passenger door switch one I unscrewed it and grounded it and got 12.8 or so volts - but it doesn't turn the interior light on - no big deal really I suppose?

I had tried to swap the switches over from the drivers side - but the screw appears to jam when about half way out so decided against tempting fate with a snapped off screw and tightened it up again...