Garageband: Smart string composition disappeared

Hello everybody, I have a problem with a garageband file. I made a composition with guitar track registration and a lot of simulated instruments (something like 11 track). When I saved, I tried to export the file in soundcloud, but when I have listen the track, there was no sound. I return on garageband, and the smartstring track was empty: there were only the green rectangles, without notes. What appened? Can I resque the missed music? It was a great composition, I might became famous. Nothing