Depennds on what you want to see as the column header - can't work out what is required from your posted code but here are some suggestions
Format converts to text so suggest you need to choose a string which will sort correctly if you want the columns to be in order - such as these
Expr1: Format([Recharge_Date],"yyyymm")
Expr1: Format([Recharge_Date],"yyyy-mm")
Expr1: Format([Recharge_Date],"yyyy mm")
If you are not worried about the order you can use month names e.g.
Expr1: Format([Recharge_Date],"yyyy mmm")
Expr1: Format([Recharge_Date],"mmm yyyy")