[Solved] Matrix device has not been detected

I was able to succesfully run the everloop_demo, but after restarting the Raspberry and the Matrix creator I now always get the “Matrix device has not been detected” error message when I try to run the everloop_demo and any other demo’s. Any suggestions?

Works fine now. I think it was caused by other .py code which was running at startup and also controlling several pins of the Rpi.