Right it might be because you haven't finalised the disk to be played on non-recording players.
Or like you say the disk type is different. Look in the instruction manual to see what type your recorder can record and what type your player plays. You want to match the types so it works (will be + or -)
Thanks Si Pi. I guess it could be because I haven't been finalising the disks properly; will have a good read of the book that came with it; think I'm using the right disks.
Cheers.