Please test yourself why the second step of this exercise is not working any more. The condition for the correct answer is authored as: <condition xref="exer1_def_average_slope_good"><diagnosis><achievement value="1.0"/></diagnosis><syn_eq>$lambda(x,(y_coord(Q) - y_coord(P))/(x_coord(Q) - x_coord(P)) -x)$$0$</syn_eq></condition> where the variables y_coord and x_coord can only be enterd using the input editor (tab "Allgemeines"="General"). Instead, when I give that correct answer, the exercise starts again, telling me that I didn't input anything.