What cancelles sound unintentionally?

From time to time I play with my Live II and suddenly I see the sequencer playing but I don't hear anything more. WTF has happened?

1st culprit inadvertently I' ve activated mutes

2nd culprit: I've unintentionally changed the current sequence

Are there further causes?

you inadvertently have recorded mutes and have the mute rec\play option activated in the preferences

Thank you! I'm going to check my Preferences / Sequencer settings. I think it is time for a further sticker on my MPC housing.

The problem isn't in your preferences or settings. To verify Hyena's very likely hypothesis, delete the track's automation.

You'll want to go into list view and look at the track. If you've got track mute automation you should see an event on the top of the track... and you won't be able to delete it until you get rid of all of the track mutes within the track.

@Jean-Marc Liotier and NearTao: THX a lot for your insights and tips!