Visual Studio.Net

One of my collegues have a strange problem. When he imports a porject made and runs the debugger the following error occurs:

Code:

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Error while trying to run project: Unable to start debugging on the web server. The project is not configured to be debugged.

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Any of you have an idea of what goes wrong?

edit your web config :
<compilation defaultLanguage="vb" debug="true" />

Hi Rio, thanks for your reply, the strange thing is that he HAS applied the code you wrote!
There's no problem when he debugs a project made on his own pc, the problem occurs when he imports projects.