[Wlug] Fedora 15 and Burning CD

I want to burn a copy of fedora 15 32-bit on a CD but my installed fedora 15 64-bit isn't letting me. When I put in a blank CD it tells me it has 137.8 MB free and won't let me select that as a burn destination. It shouldn't be 137.8 MB free as a blank CD has more space. To get it working I decided to try burning to a DVD. Space seems correct there but again it doesn't allow burning.