crystal report display

There are 2 fields in my report. One is the month number and the other one is a year.

fiscal year starts in June. So we are in fiscal month 6 and fiscal year 2012 now.

I have these 2 fields in the crystal report and I need to create a formula ,

that will display the Oct12 And then I need to supress the year - 12 . I might have fiscal year 2011 also in my dataset so it needs to be sorted in ascending order) , Right now it just displays as '5 2012'

. It needs to display as Oct

So I created a formula to convert number number to name: =Month(ToDate(FormatNumber([month_no];"00") ;"MM"))

BUt that gives an error in the version of Crystal report that I am using.