Hi, I think you need to check 'Expression' as your sort option (3rd down, 2 above Numeric Value from your last screen shot) and enter the expression - Sum(Complaint_Value) - and check Descending. Cheers, Chris.
In the sorting tab under the expression , use RangeSum(Above(SUM(Complaint_Value), 0, RowNo())) for your sort if you are looking to sort based on the accumulation . when you select sort based on Y-Value it takes the first expression for the sort which is why you got the sorting of the first expression correctly
When you sort by "Y-Value" in a pivot table, it is sorted following the first expression. Said so, you may switch to straight table so you can sort the chart by any of the columns (I don't see the need of a pivot table in your example so, if you can use a straight table I would do it).
If you need to keep using a pivot, you can create a first column to sort the table (with "RangeSum(Above(SUM(Complaint_Value), 0, RowNo()))" in your case) and then completely hide the column (you can achieve this with a macro).