Kan ikke debugge i Visual Studio .NET

Jeg kan godt builde men når jeg vil debugge skriver den:

Error while trying to run projekt: Unable to start debugging on the server. The serverdoes nit support debugging of ASP.NET og ALT Server applications.
Run setup to install the Visual Studio .NET server components. If setup has been run verify that a valid URL has been specified.

You may also want to refer to the ASP.NET and ALT Serevr debugging topic in the online documentation. Would you like to disable future attempts to debug ASP.NET pages for this project?

Her kan så svares Ja, Nej eller Hjælp.

Hvad skal jeg gøre for at få det til at virke?