I am having the same issue, where some of the data does not render in the chart, but it is ok in a table. Can you explain a bit more about your solution? Did you change all of the series output into integer? or did you change the grouping to integer? Any help is greatly appreciated.

--// EDIT

I figured out the issue that I was having. I was overlooking a warning of aggregate function trying to sum multiple data types. I then found this article that helped me visualize the issue:

http://blogs.msdn.com/b/sql_pfe_blog/archive/2009/07/10/sum-of-a-sql-analysis-services-calculated-measure-within-a-reporting-services-report-gives-error.aspx

So, I updated my series value with =SUM(CDBL(xx.xx.value)) and all is well in the world....