Crosstab column Group Header

[kreynolds]

I have a report that uses Dates(Group By Month) as the Column Header in a crosstab with the format of "yyyy-MM". When I use this format it works great but I now need to format as "MMM-yy" which then changes my sort. and puts August before Jan. I understand why this is happening I just don't know of a soulution to have a needed format of "MMM-yy" 

The Expression that I am using for my column header is.

      (new SimpleDateFormat("MMM-yy")).format($F{DateGroup})