pivot table / chart default sorting

Question

What is default sorting for excel 2010 pivot table and charts I have a "Year month Week" column in my data sheet which I am using as row label, excel pivot table renders it arbitrarily

like in data sheet I have data in the following order

2010 October Week 1
2010 September Week 1
2010 September Week 2 
2010 September Week 3
2010 September Week 4

but when I use this in pivot table it generates row labels as

2010 October Week 1
2010 September Week 3
2010 September Week 2 
2010 September Week 4
2010 September Week 1

I want pivot table to show row labels exactly in the same order as it is in data sheet

Answer 1

To answer your question, per Microsoft:

Excel uses the following order for ascending sort: numbers, text, logical values, error values such as #REF! and #VALUE!, and then blank cells.

It might be a good idea to check formatting to ensure the data is being stored correctly.

Answer 2

You can sort on the field in the Pivot Table - choose "More sort options" then an appropriate order, then "More Options" and make sure it is ticked to automatically re-sort if new data is added.

Your biggest problem here will be the sort order is arbitrary - if you choose alphabetical this will not work very well for the month names. You would be better to either use a week number across the whole year or actual dates (eg for week commencing 3/10/10, 10/10/10, 17/10/10 etc).