Ones again thank you!


I have implemented the formulas in my real excel program now and it works
perfectly.


I take it, that with the second step(N2) you mean (M2) etc.
Yes

Not doing it correctly will cause the problems you describe.
However, I can't replicate the #REF! error. Please check
the formula in N2 again and check all references.

You where right, I had a error in my formula.