Trying to get SumByColor working

Hi all, I was trying to add in a function to add a column based on row colour and came across the "sumbycolor" macro. I've added it to the attached sheet but for some reason it doesn't calculate properly for all columns (see for example Client 2 & Client 4). Have I gone wrong in the formula somewhere?

(Btw I was originally asking in the Formulas thread about the SUM function but then found out VBA/Macro may be the way to go, so sorry for any duplication of posting!)