park assist problem

[carmel120]

Address 76: Park Assist (4E0 910 283 A)

17:06:05
14.50 V Sensor Voltage Supply
Not Oper. Function Button
0.96 ms Rear Left Sensor
0.78 ms Rear Left Center Sensor
0.96 ms Rear Right Center Sensor
0.91 ms Rear Right Sensor
0.88 ms Front Left Sensor
0.98 ms Front Left Center Sensor
0.80 ms Front Right Center Sensor
1.06 ms Front Right Sensor
ON Confirm. Sound (Reverse Gear)
Tuesday,10,March,2015,17:22:35:65217
VCDS -- Windows Based VAG/VAS Emulator
VCDS Version: Beta 12.10.7 (x64)
Data version: 20130802

hi the parking aid is not working and I checked there is no fault codes present and I have put my ear to the parking sensors and they are all clicking.
there seems to be a problem with the button the indicator light does not flash and everything works as it should for about two seconds.
on the mmi screen it all present and working.
the measuring blocks stay at 255 all the time

cheers trev