The car will not flash indicators (or make a plip noise if enabled) it the whole vehicle is not secure - Doors not shut, bonnet slightly open or boot not quite shut. Is the door open warning light (red picture of car with door open) lit when all doors/boot are shut? If so then it is to do with doors/boot/sensors if not it is probably to do with the bonnet/sensor.

Make sure boot/bonnet slammed well shut!! On my Skoda Superb (same setup presuming Passat is 2005 model or earlier) you have be quite firm with both the boot and bonnet.

Double check the bonnet latch switch as this is a common failure due to its exposed position.

Does the door opent light come on when each door or boot is seperately opened (checks sensor for each)?

Also, you can temporarily disable the sonic sensors by pushing the button on the door A pillar (low level near drivers side seat height adjustment ).

Do you have have wet carpets? Very prone to water leaks from plenum chamber etiher due to badly fitting seal around the pollen filter and/or blocked drains under the battery. This can play havoc with the control module.

found problem thanks to your help Big John.

Bonnet release catch is not throughing the micro switch. held switch down and the alarm set. will have to take off catch to see why its not touching.

Again many thanks and keep up the good work.

Rich