Pivot tables and ordering of dates

Hello,

I have converted standard dates into just a month and year, using the formula I found on this site. I have also sorted my original table of date by the dd/mm/yy column to get the data into an assending order. I am not trying to pivot table out the information such that I can see by year and month the number of orders I am raising. The only problem is the data is being diplayed by year, but then by month alphabetically - how can I arrange this to have the year and month appear as per the calendar.

Thanks,
simon