transponder bypass problem

Installed a Compustar Alarm/Auto start on a 99 Mercedes ML320 with a universal transponder bypass kit.Customer had ordered a valet key for this which was sealed in the original bag,tried starting vehicle with all the keys(2 originals,1 valet) and it started with all.
Install went fine and the autostart worked okay for a good 15 times or so.Then disaster,vehicle wouldnt start either with the original key or remote.I disconnected the battery terminal for a while and then vehicle started with only the valet key.The original key just got erased and wouldnt start the vehicle.The second original which was not near the vehicle also works.
I have read somewhere that the original key had to be reprogrammed by the Dealer after a few weeks of using the autostart.
Has someone experienced this problem and would reprogramming all the keys solve the problem or would it delete a key again?
Any feed back will be very much appreciated.

the only method you can use on that vehicle for transponder bypass is using a Viper556u that hardwires into the immobilizer ring wiring and stay ON until you shut the car off with the key. If the car sees one key then the key code change while running it will delete the second code presented.

The reason the valet key works and his second original works is they've never been seen by the vehicle at the same time.

get the first key reprogrammed, and get a 556u and follow the directions that use the pink wire to keep the 556u on after takeover.

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Shaughn Murley
Install Manager, Dealer Services
Visions Electronics
Red Deer, Alberta