Device must be a disk.  Enter a disk device (such as, DKA0:).

    Meaning:  You entered a valid device but it was not a disk device.

    Action:   Specify a valid disk device.  Press PF3 to display a list
              box of known disk devices.  Use the arrow keys to scroll
              through the selection options and press Return to select a
              device.  Selecting a device from this box places the
              selection in the name field.

              If you do not want to select a disk device press PF3 again
              (or Ctrl/Z) to cancel the box.