Logic Pro Trumpet Part Doesn't Play Back.

[sus4]

I had this problem once before and don't remember how I fixed it. I checked the Step Editor window and don't see anything un-usual. I see all the notes in the Score Editor window. The 3rd trumpet stopped playing back. Don't know what I did. I'm also using ARIA player. When I open ARIA the volume is down to zero on that trumpet part. When I raise the volume it still doesn't play. When I close ARIA and re-open it again the volume is back down to zero. So I don't know if it's Logic Pro X or ARIA.
Thanks for any help.

 

[sus4]

PROBLEM SOLVED. Don't know why, but I rebooted Logic Pro X and the 3rd. trumpet is back. Sometimes when you reboot it fixes things.