I was also facing the same problem. Thanks to your suggestion I solved my problem. In my case, I was having problems with two parts of the formula question. The variable of Part 2 depended on the Variable in Part 1. So for a completely satisfying Regrade, I had to input the equation for the variable used in Part 1, and the equations for two variables in Part 2, (1) equation for variable in Part 1, and the equation for the variables of part 2 which depended on the variable of Part 1.