I have an error likewise:
ERROR: Could not find an XML setup file in the package.
Now, I have read and searched the forum and an well aware of the ultra-annoying 'people trying to install a plugin from the joomla install page' issue.
I am trying to install from the CB plugin page.
background:
It worked fine installing to Joomla 1.0.15
I can't get it to install to Joomla 1.5.22
both sites on same server so it isn't php related.
I checked directory permission in help / system info
read all posts and made sure component plugin directories 777 etc.
tried kicking site out of legacy 1.0 mode and installing
tried pretty much everything, would appreciate if anyone can help, just purchased for this reason.
BTW - I did this because strangely, 100's of people a day were creating accounts, even though email verification is checked and moderation on, I still see their accounts in the DB regardles, even after rejecting accounts. I assume this was due to some security issues with 1.2
Thanks again.