WebService Error: The target principal name is incorrect

Hi all,

I've managed to consume a NAV-WebService from NAV when the WebService is running on the same machine as the consumer (means 2 different Services for 2 different databases on my local notebook). Now I try to consume a WebService which is provides from a different machine (but in same domain) and I'm receiving an error "Der Zielprinzipalname ist falsch" (The target principal name is incorrect)
Does anyone have an idea how to solve this?

Thanks
Thomas