X axis values repeated in report chart widget

I have a requirement in which i need to show a count of new and closed items for each day. I executed following OQL

SELECT distinct
sum(case when Case_Status!='Closed' then 1 else 0 end) as NoOfNewCases,
sum(case Case_Status when 'Closed' then 1 else 0 end)as NoOfClosedCases,
changedDate
from MyFirstModule.Case_Details
group by changedDate 

 I have given the changedDate column in horizontal axis. As you can see below, the date is repeated. Can somebody help me with this.?