Usb Debbuging is not working I have Samsung Galaxy J1 4G, Android 4.4.4 KitKat and Windows 7. Previously I have installed Intel App Preview, disabled and then enabled USB debugging and it works. Then, I uninstall and reinstall Intel App Preview and USB debugging is not working.
I experienced a similar problem, I solved by remove and install samsung drivers from my computer.
In order to see if it is a 'driver problem' try to connect your phone in debug mode to another pc, better if it is running linux.