"Active directory can't be reached" in AX 2009

Scenario:

Inside AX 2009 on Administration Module>Common Forms>User> Import, we try to Import the user by selecting the Domain, Our Domain is google.com and we are trying to import the user from yahoo.com, and now search for the user gives the error "Active directory can’t be reached"

Note: 1) When we put DNS of yahoo.com we can find the user list.

Note: 2) After trusting domain we can access the files folders and yahoo.com user list.

yahoo.com is on Windows 2003 r2 and google.com is on 2008 r2 also they are using Static IP addressing.