What does this error message mean?

[reg@xxxxxxx]

Linux  kernel 2.4.1, Iomega Zip250.
Ive had this working with earlier kernels (and devfs?), but am trying to move 
to
2.4.1 and I dont know what to make of the following error message.

    [root@orion reg]# mount /dev/ide/host0/bus1/target1/lun0/part4 /mnt/zip4
    /dev/ide/host0/bus1/target1/lun0/part4: Input/output error
    mount: /dev/ide/host0/bus1/target1/lun0/part4 has wrong major or minor 
number

Listing /dev/ide/host0/bus1/target1/lun0 shows

[root@orion reg]# ls -lai /dev/ide/host0/bus1/target1/lun0
total 0
    355 drwxr-xr-x    1 root     root            0 Dec 31  1969 .
    354 drwxr-xr-x    1 root     root            0 Dec 31  1969 ..
    880 brw-------    1 root     root      22,  64 Dec 31  1969 disc
    881 brw-------    1 root     root      22,  65 Dec 31  1969 part1
    882 brw-------    1 root     root      22,  66 Dec 31  1969 part2
    883 brw-------    1 root     root      22,  67 Dec 31  1969 part3
    884 brw-------    1 root     root      22,  68 Dec 31  1969 part4

Im really not sure what 'wrong major or minor number' implies here.
Any thoughts to get me on track?



-- 
                                        Reg.Clemens
                                        reg@xxxxxxx