Unable to access portal service from web service..........urgent

Hello All,

I am using EP6 SP9.

I have created a portal service and created web service from the portal service.

Now when i try to access the web service either from NWDS Enterprise portal view i get this error.

<b>The user Authentication is not correct to access to the portal service <service name> or the service was not found.</b>

<i>I get similar error if i try to access the service from C# Client saying User Authentication problem.</i>

Please tell me where to mention Authentication details.

regards

Santosh