had a custom domain .if you had
add you blog in webmaster tools
before adding your domain to your
blog then you have to add you blog
url again ..now you had to add you
custom domain url in webmaster tools.
also add both www or non www url
of your site and set your preferred
domain name in webmaster tools
you can select any one from option
how to set preferred domain in webmaster tools
first login to your webmaster account select your
site .
there at the right top you see gear icon
select setting from option