Login failed for user '(null)'.

Greetings,
Can you post your source code here? And can you login directly using SQL built-in tools?

It sounds like delegation is not working.  I'm assuming you;ve got an ASP.NET app trying to access SQL on another server.

You can either use a SQL login in the connection string or get delegation working.  

Here are some articles to help implement delegation:

http://support.microsoft.com/default.aspx?scid=kb;en-us;810572
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vsent7/html/vxconASPNETDelegation.asp
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnpag2/html/PAGHT000023.asp
http://odetocode.com/Blogs/scott/archive/2005/02/24/1053.aspx

hi,
 i tryed using <identity impersonate =" True"/> but no difference
and in my connection string i removed integrated security = sspi and it now have a different error
saying this
Access to the remote server is denied because no login-mapping exists

Sorry, didn't catch that you were using a linked server.  I don't know about login mapping, but delegation requires more than just turing on impersonation. It allows the first SQL setver to access the second SQL server using the original credentials (the password is not sent, only the user ID and a "ticket" authenticating the user).

Delegation requires some setup in Active Directory as well. In addition, the two SQL servers must be communicating via TCP/IP, not Named Pipes.  THis can be checked by running a Trace on the linked server and accessing it from the first server.

hi,

well what i don't understand is that when i run the stored procedure form the query analyzer it gives the same error saying Login failed for user '(null)'