can't get midi playback in Nuendo

[midge]

Hi

I'm using a late version of Nuendo. Yesterday, everything was fine, but no I can't get my midi tracks to play back.

When I open the key editor and click on the notes I have input, the VST instruments play the sounds, however when I click on the piano roll they do not, and when I hit play, there is no midi playback, only my audio tracks.

I haven't got anything soloed or muted.

HELLLLLP!!!!