I can't get passed this message FSX Not Running.

I am using the demo version of flightsim, is this the problem?
I have installed simconnect, that error had me stumped for a while
I am familiar with arduino

but i just get the message at the top in purple fsx not running.

I'm off to the pub with the dog now, would be great to get an answer.

What I'm doing this for
I am developing some of the code for project that moves a model plane, up down etc in step with Flightsim, got the model susses and the movement and calibration. just need to get the info from flightsim. to tie it all together.