You've got it all wrong!
You have to point only www-less A-record to WWWizer.
Record with www must be pointed to your hosting provider.
If you already made this change and still see this message wait until your DNS updates.
DNS setup for Google Sites
Someone made a mistake and pointed address that includes "www" to WWWizer.
We are not controlling their servers and unable to help in this case.
If you can, please contact site owners and tell them about this problem.