GTN750 Black screen in A2A Comanche

[Slaterma1234]

Hello,
When I load up the A2A Comanche with the GTN 750 I am left with a black screen even when everything is on.
It works in the BlackSquare King Air that I use. 

I looked for an update on the TDS Manager and it says I am using the recommended version.  

GTNXI Trainer V: 3.6.4.0
Flight sim v: 1.0.3.0

This is in MSFS2020.

Help Please!