Nero 7 problem

I backup my Mp3s on a DVD-RW and update it every few weeks. After launching Nero and inserting the DVD, the software compares what’s on the disc with the hard drive folder and adds the newer files. That worked fine until a recent format. After reinstalling Nero, I can’t make it refresh and recognize the new files. It will allow me to add individual files (if I could remember which ones are new), but it can’t find them for itself.

I’m not sure if I’m explaining this adequately, but it’s driving my buggy. Can anyone help?