Rangesum not working after selection

[Arun_141]

Hello Experts,

I am using Rangesum with above function to get cumulative sum, expression is working fine ,but when i select a month  in the chart , it's value changes to original sales value for that particular month, but my requirement is to show the cumulative for that month. Please help

expression- RangeSum(above(sum(Sales),0,rowno()))

Sample data 

Month, Sales
1,10
2,0
3,40
4,30
5,10
6,10

After selecting month 4 in the chart it is showing sales assigned with Month 4

 

Required 

It should show cumulative for the month 4 i.e. 80 (10+0+40+30)

Thanks is advance.