Webcam won't work correctly

When I open programs like Skype or anything really that uses a webcam, nothing can be found. I can find it in my integrated devices and it says everything is fine. The weird thing is that it isn't broken. I can use it with a specific Diagnostic software. I download it to try and fix the problem and when it did a test, it turned my webcam on, but none of my other programs work. Only that one, and that one is just meant to make sure everything is working properly. I have a Windows 7 OS. Help??