Hi,
Sorry to answer so late.
Site verification worked very well for me. In my case, the problem was the domain access from outside, but with a little help from our administrator, the problem was solved.
In the last month I verified with success 2 sites ( different domains) .
What you have to do, is to create the exact file requested by yahoo on your domain/site and be sure that it can be access by anyone.
My advice, verify your domain access
Regards,
Ionut