SECOND disk bad or incompatible
The second floppy disk used in a Diskcomp command does not have the same format as the first floppy disk, is unformatted, or has an unrecognizable format.
Make sure the floppy disk is in the drive and the drive door is closed. If it is, then try removing the disk and reinserting it. After that, if this message reappears, you will not be able to use this disk with the Diskcomp command.