Some themes working, a few are not

I’ve downloaded multiple theme from this site. Most have worked without any change on my part. I’ve downloaded a couple which when I try to activate them give this error:

Theme xxx is not defined
component/frontend/_init_py (warning)

I can’t determine the source of this problem. Anyone have any suggestions on where to look to correct this error?

you should post your config and the full error

I found the problem… since I copied both files from the Internet, they had an extra char in the file.