Reporting Services :: SSRS 2012 - Scatter Chart Isn't Showing All Data Points

I have a scatter chart in SSRS (SQL Server 2012, Visual Studio 2010) that is producing the following:

There are five data points on there, however the result set I am using has 10 rows (a 'Completed Date' of datetime and a 'Lateness' integer whose values can be positive or negative.

This is the Dataset and the results it produces:

SELECT DISTINCT TOP 10
a.ACTIVITY_NAME As [Activity Name]
, ad.COMPLETED_DATE As [Completed Date]
, ad.DAYS_LATE As [Lateness]
FROM ACTIVITIES a
JOIN ACTIVITY_DATA ad ON ad.ACTIVITY_ID = a.ACTIVITY_ID

[code]....

How can I tell SSRS to show every data point in my chart?