Why is the order improper, while using the Month Range option? For example, I selected Nov 2010-Jan 2011. Week 1 of Jan 2011 got displayed first.
Modify the 'OrderBy' column in the crosstab area of the KPI as 'DATE_KEY - Ascending' to get the month range in the ascending format. After doing the changes, if you select Nov 2010-Jan 2011, then the Week1 of Jan 2011 appears at the end.