[dizzyg]

I have created successfully a backup file on my tablet (mobileSheets_date.msb) file with my library of music pieces (126 in total) . However when I restore this file to an other device (smartphone) I am left with only 8 of these 126 music pieces. The 5 playing lists and 3 collection lists are restored. 
If I look to the progress when the backup is running it seems that only these 8 pieces are send to the backup file.

Any idea what can be wrong?

[Zubersoft]

It sounds like you have installed MobileSheetsTrial and do not have the paid version. That would limit you to only 8 songs in the library. You have to install "MobileSheets" in order to have more than 8 songs in the library.

Mike