When you are searching for a user on an Active Directory Users and Computers, the search result does not return which OU the found user is a member of. To find out which OU the user belongs to try the following.
1.) Goto Active Directory users and Computers
2.) Goto menu “View” and enable “Advanced Features”
3.) No find your user and check his/her properties. You’ll see that there will be an additional tab called “Object”, which shows the cannonical name. Hence the tree to the OU will be displayed.