Error App Domains: www.c-o-r.co.uk/civilisation_of_the_rough is not a valid domain.

Hi There, hope all is good.

Just trying to set up the FB plugin but I'm getting this error while setting up the api keys in FB - "Error
App Domains: http://www.c-o-r.co.uk/civilisation_of_the_rough is not a valid domain."

Any idea why its saying this?

Thanks

Mark.