Call Project Server Interface web method from an msi installer | I'm using a Visual Studio web setup project to install an application that extends the functionality of Project Server. I want to call a method from the PSI ( Project Server Interface ) from one of the custom actions of my setup project, but every time a get a "401 Unauthorized access" error. What should I do to be able to access the PSI? The same code, when used from a Console Application, works without any issues.