Upgrade 6 -> 7 not working.

["fb" <aikus freemail hu>]

I tryed to upgrade the fc6 with the Fedora 7 DVD. 
Installation menu offered the upgrade of the recent 
version on hda2, but after my choose that version I got an 
error message:

Error mounting device hda2 as / : no such file or directory 
devices in /etc/fstab .
Should be specified by label, not by device name.
Click to reboot.

What can I do?

TIA: fb