Date Function in Expression

[#1]

Hi All,

i need help in getting sun function flexible. currently i have 3 columns:

ID           Date                    Qty

1               28/3/2014          100

1               27/3/2014          1000

1               24/3/2014          2000

in expression i use below and i get sum value for that date:

Sum({Date = {'$(=Tdate)'}>}Qty gives be 100 ........ Assume variable Tdate = 28/3/2014

Now i want in same expression and get value of 1100 from Date 28/3/2014 & 27/3/2014

please advise what needs to be changed

thanks

[#2]

thanks