Error in loop of cruisecontrol model

For school I have been working on a model of a "cruise control". It is supposed to model a car that accelerates to a certain speed that can be selected. Once it reaches that speed it is supposed to hold that speed until the simulation is stopped. I've made the moddel in seperate parts first (for example: the gearbox and drag calculations). Those individual parts work well together. When i put them all together and connect them so that they loop I get an error message in one of the blocks because it cannot identify the signal dimension. I have tried everything I know but have not yet found any solution.

Can someone see what I am doing wrong?