Instrument Track Grayed Out

[adam79]

I've been having a reoccurring problem with playback of VI drums. I'll record the drums on an Instrument track, save and close the session, but when I come back later to open the session, the Instrument track with the MIDI notes is grayed out.. and won't playback. If I create a new MIDI track, set the output to the Drum VI and drag the grayed out Instrument track to the MIDI track it'll play.

Has anyone had this problem and figured out what's causing it? It's starting to get really frustrating.

Thanks.