Group by Week in SSRS fetch Report and Sum the Hours for each week

Question

I have create an SSRS report using fetch xml on time entry table, with grouping by week using DATEPART("ww", Fields!msydn_date.Value) expression. it works but it show the duration of first day in the week not the sum of duration of entire week. My data should look like this

Resource	Week1	Week2	Week3
Resource A	80	70	80
Resource b	40	60	30
Resource c	20	10	60

But my data looks like this which is the duration for first day of the week not the entire week duration

Resource	Week1	Week2	Week3
Resource A	8	7	8
Resource b	4	6	3
Resource c	2	1	6