Midi editor notes won't sound when clicked on

[yehaabob]

I've probably turned something off, but I don't know what. I'll record an instrument track using expand, get into midi editor, and when I click the individual note, no sound. I can move the note around, but no sound. when I play it back, it works just fine. But to edit each note individually, no sound. I have protools 10. thank you in advance-

[yehaabob]

I can go back to older sessions, and the midi editor works just fine. But it won't work in the current session, or even a new one. What have I turned off? Thank you-

[yehaabob]

OK! I found it! I knew I had hit a button. Took me two days to find it, but I know where it is now!!! Yahoooo-

[studios111]

So what is this button? i'm having now this problem as well