Boot release
 

I have used my 1998 C230 Kompressor for 6 years now. There is a problem, the boot won't open after having driven the car around until the car is turned off. Neither with the release button in the car nor key fob. After switching the car off and on again, the boot will open until when you reach the speed at which the doors will lock automatically, then the boot will cease to open even when you make a stop. Please help