Move Database button greyed out

I have two drives, both setup as Mac OS Extended (Journaled). So I'm not sure why it's greyed out.

I'm trying to use rekordbox across two machines using dropbox as detailed in your instructions here.

When I open the second machine it's not pulling up my collection, hence why I was investigating what might be the issue. Is there a thread somewhere for people having difficulty pulling it off?

Is that drive connected via USB?

No, it's a second drive inside the machine

Ah, yeah, if you've got it on a drive occupying the optical drive bay, that drive is not supported within rekordbox as it's a non-standard device according to the OS. Sorry.