Sum of range in ActiveCell

I have values in Columns C & D. The ActiveCell is moved dynamically in Column E. For this example the ActiveCell is Cell E24.

I want to place the value, of the sum of the range D2:D24 minus the sum of the range C2:C24 in the ActiveCell.

I believe the approach should be to create a range (call it DRange) from ActiveCell.Offset(0,-1):D2 and then create a second range (call it CRange) from ActiveCell.Offset(0,-2):C2 and then place the value of DRange minus CRange in the ActiveCell.

How do I do this?

I resolved it by using the date column to find the last instance and then inserted the value using SUMIF formula!