Need Help the the domain name resolution

Dear All
In the past few months i found in my webmaster tools all black links link to my home pages was gone
I continue build links link to my home page ,but no effect at all!
I sudden realized maybe the domain name resolution problem!
I check the url:www.mydomian.com in google but the result was the: mydomian.com does it means? my www.mydomain.com this url not index by google?
So it means whether I do how many BL to my www.mydomain.com, will no use!
So what should i do now?
any good suggestion?

Google normally works this out themselves, although I'm pretty sure you can tell which to use in webmaster tools. I have seen that before though, it generally means that google has a problem with your site. Have you changed anything else? IF it was working before and not now it could be something else.

I just 301 the mydomain.com to www.mydomian.com to check out any change