WCF service authenticating problem

[=?Utf-8?B?R3JlZ2k=?=]

Hello all,

I have problem with WCF service authenticating. Please, take a look at the
following code:

ProductsServiceClient proxy = new
ProductsServiceClient("NetTcpBinding_IProductsServ ice");
proxy.ClientCredentials.Windows.ClientCredential.D omain = "DAGREGI";
proxy.ClientCredentials.Windows.ClientCredential.U serName = "Bert";
proxy.ClientCredentials.Windows.ClientCredential.P assword = "Pa$$w0rd";

ProductsServiceClient is a ServiceContract. If I comment out three lines
with credential info, everything is fine. In other case I received following
exception:

SOAP security negotiation with 'net.tcp://localhost:8083/TcpProductsService'
for target 'net.tcp://localhost:8083/TcpProductsService' failed.
See inner exception for more details.

Inner exception:
System.ServiceModel
The message or signature supplied for verification has been altered

Example is taken directly from WCF Step By Step book, and it should be
working.
I have no idea what is wrong. If you need some more information, please let
me know.

Thanks!

--
Gregi