Edited to add: After posting my reply, I noticed that you mis-posted your question in the QlikView forum. I have no idea if my answer is relevant for QlikSense, but I'd expect that to be the case anyway.
Generally speaking, it is not possible to sort pivot tables by expressions out-of-the-box.
There's a single exception - you can sort by the first expression's value, as it pertains to the first dimension. For example, if your dimensions are Customer and Month, and your expressions are Actual Revenue and Planned Revenue, you can sort your customers by their total Actual Revenue (without impacting the sorting of months for each customer). This can be achieved using "Y-Value" in the sort screen.
More information - and a proposed workaround I have not personally tested - are available in this thread: Sorting in pivot tables
An explanation of why you can't sort pivot tables by expression, as posted by QlikView's hic
hic Mar 24, 2015 4:59 PM (in response to sree anaarasi)
Not possible. And it is not a limitation of QlikView - it is a consequence of the properties of a pivot table.
A pivot table is always sorted first after the first dimension, then the second dimension, etc. This is necessary since the rows are grouped first after the first dimension, then the second dimension, etc. If you want to sort after an expression, you should use a straight table instead.
An other aspect is that you try to sort the "Document number" after "Row". But this is not possible since a document can have several row numbers. See also Use Aggregation Functions!
