We can predict that your objfun has a place where you use Variable(Parameter) where you should have Variable.*(Parameter)
That is, you try to use implicit multiplication, but MATLAB does not have implicit multiplication, and the operation you are accidentally invoking is indexing instead of multiplication.
In MATLAB A(B) is always either indexing variable A at offset B, or else calling the function indicated by A passing in parameter B. A(B) in MATLAB never means to multiply A and B.
