Can't sort pivot tables

I have created a pivot table out of a data sheet in a Calc document. This table has one page field and several column fields. Everything works as expected, with one exception: The sort function of, the which is part of the little drop down menu in the head of every column, doesn’t work. When ever I choose to sort the table according to certain column, absolutely nothing happens, whereas the filter option does work as expected.
Does anybody have an idea, what the root of this problem might be?

For clarification see the screenshot:

There are three answers to this question: “How to sort pivot table by data?” Any help there?