Clone not showing in StartUp Disk, and cannot dismount Destination Drive

[Dial]

Ok, once I did a restart I had no further problem dismounting the external drive.

As to the rest: I've done all you have suggested and still the external drive does not appear in the Start Up Disk window in System Preferences. I've given a few of my usual apps a go and they seem as usual. Perhaps all is well?

Regarding the bootability of the Macally drive. I was sold the enclosure by my local Mac service center on the understanding that it would be bootable. Indeed the first copy made was by them. I never tested it for bootability, so who knows...

Any further suggestions before I return to the service center and ask them to sort it out?