...the session was closed incorrectly. Although CD burning programs have the ability to leave sessions open so more items can be copied to the CD, you need to be very careful when doing so. If you happen to "finalize/close" the CD, you will be unable to add any addition data to it. And even if the session is left open, adding more pictures/data to the CD may make all the previous data "invisible" when placing it in a different CD device. It's a toss-up to it's reliability.
Unfortunately, my experience with "open sessions" hasn't been reliable. Maybe others are more successful at it. So instead of attempting to add pictures to an open session, I wait to burn a CD until I have enough data to fill up the entire CD. Once finalized, the CD can be read by any CD-Rom device.
Hope this helps.
Grif
I'm using ME and Nero Express which came with my cd burner which is an add on. I have successfully managed to burn my pictures to a new cd and even managed to add once or twice then suddenly I can't add any more. The cd is not full. I then have tried another brand of cd and all is well until I try a second or third addition. What could be wrong.
When Nero won't burn this happens. I open nero-burn and click on data, the screen which then comes up is blank - i.e. it doesn't show what is already on the cd
It made me think the cd was empty but it isn't, the data is there if I go into read instead of burn. Please can someone tell me what if wrong, presumably it isn't the program as it works on a new cd, so is it the cd and why does it only happen after a couple of additions?

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