Dan the Guitarman

So I want to play the score that I made. I wanted to test the software so I integrated the signature six notes from Metallica's nothing else matters. Crescendo was however "unable to play midi"... The template "dance of the sugar plum fairy" gave the same message after I pressed the play button. I don't have any midi applications in the background, nor do I have music apps like Spotify or even youtube videos opened. I tried restarting the application, but this did not resolve the problem... Please help. I need this program for school.