Installer of winform project of vs2008 does not work correctly on w7

I'm in a dilemma that a vs2008 installer does not work properly on the machines where I installed it ( Winform project installer in vs 2008 does not recognize the app.config ), the issue is that the development is in a WXP machine with VS2008, and if the installer installed it in a machine with W7 it does not work (it is installed but it does not access the app.config), but if I install it in a machine with WXP if it works. So the key question is, what factors do I have to take into account to make it work in W7? Is there any configuration? Maybe something about architecture 32 or 64? Maybe the OS in which development has to be the same as the client machines? Does anyone know anything about it and could I shake my hand ???