if(GetSelectedCount(Month)=0 or GetSelectedCount(Month)>1,round(num(max(Date_SecSales_Monthend)-MonthStart(min(Date_SecSales_Monthend)),'#,##0')), num(max(Date_SecSales_Monthend)-MonthStart(min(Date_SecSales_Monthend)),'#,##0')),'#,##0'))
what is this field? Date_SecSales_Monthend?
also why do you need help? what is the problem specifically?