Hello. I have just purchased a merc c220 cdi. It has a auto box but also can use it as a semi auto, i drove the car back home and parked it up. A few weeks later went to move it, it started fine but wouldnt select a gear. It just poped up on the dash "select gear" but wont go out of neutral. Also come up saying check transmission oil. What would be the problem? If anyone can help would be gteat