Erasing iPod

Hi
I am having trouble trying to erase my iPod.
I have located it with "Disk Utility" and got this message in red a

Verify volume failed with error Could not unmount disk

So I tried to repair it and got this message

"Repairing disk failed with error Could not unmount disk"
The disk is unlocked and I have read/write permissions Any ideas please

Regards
Teapot

Aha self help is help indeed
I ran DiskWarrior, that picked up on a few minor problems and fixed them. Then I ran Disk Utility and all is now well

Managed to sort it with disk warrior all is now fine

Isn't DiskWarrior just the best.

Glad it's sorted.