06 R52 car

Bought a after market key with transponder chip and circuit board
Installed it in an exiting cut key I had
Works the doors,
Only works ignition when:
I insert the working key and turn the key 4X to on position
then immediately insert the "new" after market key
Turns engine on every time
Problem: If it is removed from the ignition, it stops working in the ignition
ANY ADVICE PLEASE?
Thanks
Bru