I 've been syncing the ipad with my lappie, and now I am on my imac, the first notice I got was this ipad is synced with another library, do you want to delete blah blah and sync with this? I clicked no. Since then I synced with the imac's library, yet it won't let me select "backup ipad", and when I reconnect it to the lappie it does enable me with this option. Where is the ipad syncing to? I am very confused here....