I have: a service running under user account domainA\userA on hostA from domainA SPNs created for the service running on hostA for user account domainA\userA a client part of my application is trying to access resources (through remoting) from the service running on hostA but this client part is running on hostB from domainB and under the user account domainB\userB appropriate delegation settings are done for user account domainA\userA trusted for delegation SPNs set properly with no duplicates domainA and domainB have two way trust I get this error: A secuity package specific error occured: Unspecified error (0x80004005) Could you please see if there is any authentication setting I missed?