Have you checked or there are fault codes stored? DTC's?

If so, that is the main reason you cannot execute active tests. If no codes are stored, I would imagine MaxiSys should give a reason why the test cannot be done. Unfortunately sometimes the system gives us reasons which are not really understandable for the user or sometimes only a "conditions not read" which won't help either :)

It is doing the same on Peugeot cars and saying code 22.
I'm using Maxisys 908Pro and thinking on returning back to seller.
Can't do a proper diagnosis job with this machine...
My last Delphi Ds150 never let me down like this one is doing on several things to be
honest...
Good luck mate.

 Sounds pretty crazy since , why would we bother with active tests of circuits if there wasn't a code for the circuit. However if there is a hard code that won't clear for any circuit which actually is shorted and you perform the component actuation tests through the tool, Autel does not want you to damage the tool or something on the vehicle.
    If the code does not distinguish between an open or short , just try to load the circuit with a noid light and then see if code will clear, and try again.