Rubstrol

This is a recurrent problem since I bought the Mackie control universal... from time to time the thing doesn't seem to understand what the computer is telling it... I tired of trashing the cs file and starring at the preferences in logic and reading the apple's control surface setup... At the moment the MCU ONLY RECEIVES ! if I move a fader in Logic the fader will move on the MCU but if I move a fader on the MCU the fader would go back to its initial position and no response in Logic. I tried to unplug everything and scan again but not avail. Please, someone help!