what cause InvalidCursonPositionException?

[Wu, James C.]

Hi Guys,

I am trying to query an attribute of a DN in my customerized authenticator that 
overrides the SimpleAuthenticator.  The following is the code.

                SearchRequest searchRequest = new SearchRequestImpl();
                Dn dn = new Dn(maxUidDN);
                searchRequest.setBase(dn);
                searchRequest.addAttributes("uidNumber");
                DirectoryService service = getDirectoryService();
                CoreSession session = service.getAdminSession();
                EntryFilteringCursor cursor = session.search(searchRequest);
                cursor.beforeFirst();
                cursor.next();
                Entry entry = cursor.get();

The DN is defined as follows:

                dn: uid=maxUidNumber,dc=example,dc=com
                objectClass: top
                objectClass: account
                objectClass: extensibleObject
                uidNumber: 1000

and maxUidDN is set to "uid=maxUidNumber,dc=example,dc=com"

I keep getting the InvalidCursonPositionException at the last line of the code. 
I am wondering why the cursor position can be invalid. Can anyone give me some 
clue? Thanks.

James