I record something (for example, using the techno piano).

When I double-click it and open midi editor, after I click another note, the pattern won't play back.

The pattern is there, but when I click play nothing is heard.

Then, when I close midi-editor, when I'm back on the main screen, I can't hear the piano keys at all.

If I switch to another instrument (such as bass), I can again hear keys,

but the techno will no longer be audible.

How do I fix this and what's going on?