is that because you only
I could be wrong, but it sounds like you need to move slower and closer to the reader.
The diagnostic card should light up no problem.
If you haven’t tried it yet, touch the card to the readers to ensure that there is power to it, incase it has been disconnected or yet to be connected? Is that possible? It sounds like the system has not yet been set up.
Are you doing a bench set up?
Are you wiring up a new system or upgrading an old one?
The xFDs will come in handy 
when you are trying to find the best orientation to present your NExT.
This is probably just putting out more power