Windows &, Advanced Folder Sharing problem

Windows 7 is on a Windows Domain. This computer has a folder that I want to share with a user on the domain. When I try to share the folder, and go to enter the user name in the "object name to select box, it cant fine the user because the name in the "from this location" is pointing to the local machine and I can't change it to the domain.  I tried domainname\username and still no luck. How do I change the " From this location" to the domain where the user account resides?

Thanks in advance.