Formula Not Calculating

Hello,

This is probably a simple fix that I am overlooking, but I am very frustrated. I am trying to get the formula in row 25 to calculate. I need it to calculate when there are numbers present in rows 15-24. If there is nothing in those rows, then it needs to be blank. Simple, right? Well, those rows are calculated as well so when they don't have a return, they are blank. I can't get that formula in row 25 to calculate since they are calculated blanks. I just can't seem to figure it out for some reason. Any and all help is greatly appreciated. I've attached the file I am working on as well. It's the MILK SHEET tab.