Sum if Before a date equivalent with filters on table

[FelixT]

Hi,

I have been struggling with a formula for the past 3 weeks. 

Here's the situation:

I have a data table with data from 2005 to 2020. I need to extract a single week data from the table so it can become my report. Here's a capture.

I want a formula Excel equivalent to a SUMIF(data dates, < my week, SumWeek) in the column Sum Week T-1.

Right now I have this formula that works when no filters are applied. 

But when I applied the filters, it starts to sum only on the first row, not the entire data set.

Thank you for your help.

Felix