Thread: calling unmanaged c++ dll from c#

I'm trying to call an unmanaged c++ dll from a c# windows form application, but I'm getting a DLLNotFoundException. The dll is in my project folder, and my code calling it is:

Code:

[DllImport("id3libBuilder.dll")]
	private static extern void createMediaLibrary ( string src );

I don't know why it can't find the dll. The code seems pretty straightforward. Can anyone help?