Handling non existent values in sql query expression for ssrs chart

Question

I am using the following query in an ssrs line chart. It counts how many orders are recorded each month based on each order date.

My problem is that when a month has

Answer 1

Got it working by removing the where clause and filtering in the count aggregate.

SELECT
MONTH(Ord.OrdDate) AS 'MONTH',
COUNT(CASE WHEN @Year = YEAR(Ord.OrdDate) AND Worker.ID = @Worker_ID1 AND @ProdType_ID = ProdType.ID THEN 1 END) AS 'Worker1',
COUNT(CASE WHEN @Year = YEAR(Ord.OrdDate) AND Worker.ID = @Worker_ID2 AND @ProdType_ID = ProdType.ID THEN 1 END) AS 'Worker2',
COUNT(CASE WHEN @Year = YEAR(Ord.OrdDate) AND Worker.ID = @Worker_ID3 AND @ProdType_ID = ProdType.ID THEN 1 END) AS 'Worker3',
COUNT(CASE WHEN @Year = YEAR(Ord.OrdDate) AND Worker.ID = @Worker_ID4 AND @ProdType_ID = ProdType.ID THEN 1 END) AS 'Worker4',
COUNT(CASE WHEN @Year = YEAR(Ord.OrdDate) AND Worker.ID = @Worker_ID5 AND @ProdType_ID = ProdType.ID THEN 1 END) AS 'Worker5'

FROM Ord
JOIN Grouping ON Ord.Grouping_ID = Grouping.ID
JOIN Worker ON Grouping.Worker_ID = Worker.ID
JOIN Prod ON Ord.Prod_ID = Prod.ID
JOIN ProdType ON Prod.ProdType_ID = ProdType.ID 

GROUP BY MONTH(Ord.OrdDate)