Repeated notes don't play

Title says it all, when a line of notes are all the same tone only the first plays and the ones after don't.
This only happens when I load a MIDI.

For example I load a MIDI into Muse and middle C is hit again and again, in succession. Only the first C plays but the rest are silent. I don't know what I'm doing wrong, or what I'm not doing right. It's getting kind of annoying listening to the lack of notes.

Please respond and thanks in advance.