By saying "remote user has a valid value in it " do you mean that this is an internal object and you are able to see the user name ?
What is the realm under which weblogic is working ? From weblogic 9.2 the user name and the group name in weblogic.xml will not be mapped automatically. You will have to mention it. This can lead to authentication errors / user info not being retrieved from the system. It is required to map the role and principal name explicitly. Here is a link
http://monduke.com/2006/01/07/weblogic-91-authorization-gotcha/
Does that help ?
If possible, post a screen shot of the object graph and a few lines of code. That will help clear the problem