Sorry, I missed the parentheses on the join. This appeared to work in your test data:
SELECT [IssueName], [ArrivalDate], [ClosedDate], [tblDates].[ReportDate]
FROM tblDates INNER JOIN tblIssues ON ([tblDates].[ReportDate]<=[tblIssues].[ClosedDate] Or [ClosedDate] Is Null) AND ([tblDates].[ReportDate]>=[tblIssues].[ArrivalDate])
ORDER BY [IssueName];
I would use the Nz() function to replace the Nulls with zeros, but the IIf() is fine. As to graphs, I really haven't done much with them. You want every 3rd or 4th day? I suspect the way to do that is simply to put the dates you want in the table. I just tested by putting 1 day a week in there, and the query seemed to pull correctly. Presuming testing proves that out, you could modify your recordset/loop to put in every 3rd day instead of every day, or whatever.