cumulative sum based on a percentile calculation

[mjgenesis]

This seems extremely easy, but I can't for the life of me figure it out.  I have a table of values with a DAX calculated column containing an amount and I'm trying to get the cumulative sum of those amounts less than or equal to <= a Percentile.INC measure (called IQR3) already calculated for the group of records.  This cumulative sum total will change (as will the percentile) if filters/slicers are used on the data, ideally.  The two formulas I've tried below only give the full cumulative total, not the total of amounts less than or equal to the IQR3 value.:

CUMUL_SUM_HRC =

CALCULATE (

    SUM(Table1[Amount]),

    FILTER(ALL(Table1),Table1[Amount] <= [IQR3]))

and.... 

CUMUL_SUM_HRC = SUMX(FILTER(Table1,Table1[Amount] <= [IQR3]),Table1[Amount])

Any help is greatly appreciated. Not sure where I'm going wrong. Thanks in advance

[Greg_Deckler · Accepted solution]

@mjgenesis Try:

CUMUL_SUM_HRC =
  VAR __IQR3 = [IQR3]
  VAR __Result = SUMX(FILTER('Table1', 'Table1'[Amount] <= __IRQ3), 'Table1'[Amount])
RETURN
  __Result

If that doesn't work, paste some sample data.

[mjgenesis]

This worked.  Thanks so much for the help.  If it isn't too much trouble could you sum up why the formulas I was trying weren't working?  I'm guessing the dynamic changing nature of the IQR and Amount variable requires a fixed use as a variable?  Really appreciate it.