Yamaha ydre testing

[Papas 73Dart]

I have the infrared scan plug and interface tool to connect on my laptop with Windows 7.
I also have the Yamaha program installed from the dealer so everything works properly.

When I try to interface with some carts it can read the cart perfectly yet on another of the same year NO interface . Has anyone run across this and if yes where do you go to test and repair problem. I also came across two different YDRE,s that had different looking plugs for the interface . Anyone come across this before ?
All the carts I am looking at are DC 48 volt carts not AC carts.