May be you missing an apostrophe here?
Sum({<Year = {'$(vMaxYear)'}, Month = {'$(vMaxMonth)'}>}Value)
In your text object try pulling these variables and see what values you are getting?
However, these days dev's are using the below Calendar script as a practice. May be you can try using this. Taken from Rob's Cookbook reference guide.
Calendar:
Load
Num(Floor(TempDate)) AS %Key_LoginDate,
'W' & week(TempDate) AS ANR_Week,
Year(TempDate) AS ANR_Year,
Month(TempDate) AS ANR_Month,
Day(TempDate) AS ANR_Day,
YeartoDate(TempDate)*-1 AS ANR_CurYTDFlag,
YeartoDate(TempDate,-1)*-1 AS ANR_LastYTDFlag,
//inyear(TempDate, Monthstart($(varMaxDate)),-1) AS RC12,
//date(monthstart(TempDate), 'MMM-YYYY') AS MonthYear,
'Q' & ceil(month(TempDate) / 3) AS ANR_Quarter,
Week(weekstart(TempDate)) & '-' & WeekYear(TempDate) AS ANR_WeekYear,
Date(TempDate, 'MMM-DD') AS ANR_MonthDay,
WeekDay(TempDate) AS ANR_WeekDay,
if(match(weekday(GLDate),'Sat','Sun'), 'Weekend', 'Weekday') as Weekend,
Text(Day(GLDate)) & ' ' & Text(Month(GLDate)) as DayOfMonth
;
//=== Generate a temp table of dates ===
LOAD
date(mindate + IterNo()) AS TempDate,
maxdate // Used in InYearToDate() above, but not kept
WHILE mindate + IterNo() <= maxdate;
//=== Get min/max dates from Field ===/
LOAD
min(FieldValue('GLDate', recno()))-1 AS mindate,
max(FieldValue('GLDate', recno())) AS maxdate
AUTOGENERATE FieldValueCount('GLDate');
Add any additional fields accordingly.
