I want to sum a range of cells whose values fall before a date that is contained in another cell. I've used sumif function - it accepts the date if I enter it directly in the criteria (eg =SUMIF(D3:F7,"<31/12/18",F3:F7) but if I enter the cell reference to the date (eg =SUMIF(D3:F7,"<A1",F3:F7) where cell A1 contains the date 31/12/18) it doesn't work.
Solved by M. W. in 18 mins