New Zip Disc 100mb Does Not Store More Than 40 Or Less Mb And Does Not Accept Fi

good evening, my question is the following. I put a new just unpacked iomega zip disc 100mb in the zip driver and want to store them on the disc. There a 2 problems. First problem is that it seems not possible to store a file on the disc, keep getting the a window saying invalid name. Tryed different names but nothing works. Until I named the file 2015... It worked and stored in on the disc. But only worked once. Using 2015 and added another number or letter, it does not store it. It does not accept any names Second problem is. Using a new disc and storing data on it only up till a certain amount of mb'sWe have been working with the zip disc for many years, and this is the fiirst time this happens. Is there an answer and solution for this problem. Would be truly appreciated. Thanks, Rachel