Sibelius - Install not Outputting Sound?

This problem usually occurs when another audio application is trying to use the MIDI input or output device (you can tell which by whether the error says MMSYSTEM IN or OUT). Please make sure that you are only using Sibelius while working on a project.

Here is how to fix this issue.

1. Open Sibelius then open any score.

2. Go to Play tab.

3. Under Mixer, click the small box. (Playback Devices)

4. Click Audio Engine Options... on the lower left corner of the window.

5. Change interface by clicking the drop-down box and choose Primary Sounds Driver (DS).

6. Close everything and restart Sibelius.