Sum a range of column rows using index/match

[iantix]

Hi,

I have a sales sheet

TEST INDEX SUM.xlsx

that matches rows and fetches sales for each row based on what date is entered. It uses index/match as shown in attached sheet cels C10 to C21 of SUMS tab.

The raw data is in the SALES tab.

What I'm now trying to do is add a MOVEMENT SINCE formula in SUMS cel C6 that takes the current total and subtracts the total at a certain date (in C5) and shows the sales movement between the two dates.

In doing so, I'm trying to sum the range of items rather than fetch one item's sales at a certain date. It's this summing of a range that I'm having trouble getting my head around.

Can someone steer me what I'm doing wrong here please?

Thanks.