Software :: GarageBand Not Recognize Some Songs

I recently upgraded from panther to leopard on a mac powerbook G4, everything went smoothly. I had about 25 completed songs in panthers garageband (version 1.1 I think, very old anyway....) I saved all the songs to a stick prior to the change. When I installed leopard, the new version of garageband refused to recognise all but four of the songs, we're talking 12 months work here ! Is anyone aware of a way of converting the songs from the old version of garageband to the leopard version? I can find no physical difference in the four songs that were reformatted automatically to the new file extension, to all the rest?