Why SSRS report brings extra row in a group and how to get rid of it?

For some reason when I run report in SSRS it shows me an extra row in a group.

SELECT      
                    COALESCE(Underwriter,'') as Underwriter ,
                    sum(case when TransactionType IN ('Policy', 'Reinstatement') then 1 ELSE 0 END) as PoliciesBound, 
                    b.MonthNum,
                    b.YearNum,
                    b.MonthName
        FROM        tblCalendar b  
        LEFT JOIN   Test_Plaza_ProductionReport a ON b.MonthNum=Month(a.EffectiveDate)   
                    AND b.YearNum = YEAR(a.EffectiveDate)
        WHERE       b.YearNum = 2016
        GROUP BY    a.Underwriter,
                    b.MonthName,
                    b.MonthNum,
                    b.YearNum

Below, is the result of the query

And this is how it looks in a report:

How can I get rid of this row or at least hide it? Thanks