[cvsnt]Impersonation failed - configuration error.

[Kernel]

Hi,all
I installed CVSNT on  Windows Server 2003 and installed WinCVS on  Windows
2000 professinal as the client.
At First I login by user administrator

Then ,I create a user named Rose ,typed cvs cmd line as follow:
cvs passwd -a Rose
and the return value is 0.

So I Alia Rose to NT system user named guest whose password is guest,typed
cvs cmd line as follow:
cvs passwd -r guest Rose
and inputed password as 'guest' ,then got return value 0.

But ,when I tried login by  user Rose
I get error message as follow:

Fatal error, aborting.
cvs [login aborted]: guest: Impersonation failed - configuration error.
Contact your System Administrator.

Any subject is welcome.