Unable to start program 'myprogram.dll'.

I started a new class using C++/CLI, but when trying to run the program I get a popup window that says:

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Microsoft Visual Studio Express 2013 for Windows Desktop
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Unable to start program 'D:\dev\myprogram\Debug\'myprogram.dll'.

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OK  
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I looked for the dll file and it is there in the Debug folder. The program is a simple 'hello world' sort of thing.

What could be causing this problem?

This is the code:

using namespace System;
int main( ){
	Console::WriteLine( "Done!" );
	Console::ReadKey( );
	return 0;
}

Worry is a misuse of imagination :)