SCCM 2012 - Endpoint Protection Reporting only using static end date

Question

I have created a subscription to the Endpoint Protection/Antimalware Activity Report built into SCCM2012/Endpoint Protection.
My problem is that I am having trouble getting the dates to work correctly.  I want to have the report automaticlly emailed out every monday morning with the status from the last 7 days (i.e. since the last monday report). 
However the subscription seems to want a static end date.  That is, every monday when the report runs it gives me a status report from the exact same 7 days.  Not the most recent 7 days. 
How do I go about changing this so it is useful and that every monday it runs, the report it creates/sends is from the the last 7 days?

Answer 1

I hope this helps (I am still testing it) but I did this by:-
"Editing" the default report such as "Antimalware activity report".
To avoid corrupting this default report before you change anything select SaveAs and call it something like "Antimalware activity report
for the last 7 days".
Open Datasets, StartEndDates and replace the query with this for the last 7 days
"select DATEADD(day,datediff(day,0,GetDate())- 7,0) as StartDate, DATEADD(day,datediff(day,0,GetDate()),0) as EndDate"
Then open Parameters, StartDate and under General change it to "Hidden".
Then open Parameters, EndDate and under General change it to "Hidden".
Save and test
I had to set the "default value" on each parameter, per Lillonel:
StartDate : =DateAdd("d",-7,Globals!ExecutionTime)
EndDate : =Globals!ExecutionTime
It looks like it is using a 7 day window now.