Not recognizing clone

[jcichy]

I've been using SD for years without a problem. Bought a new external drive, made a copy with no problem or error messages, but the clone is not recognized with an option start. Checked the HD before and after making the copy and all is well. Only the main HD shows up with an option start.
Thanks,
Jacob

[dnanian]

It's very likely mispartitioned. See the Frequently Asked Questions (Help > Frequently Asked Questions inside SuperDuper).

[Papa Art]

As I understand, it may also depend on what chip set is in the external case; I have one with a Prolific that is not bootable.