i've had a few issues where the xml conversion throws error "Illegal XML character. Had to adjust the query to this:

INSERT INTO ReportServer.dbo.VersionStore

...

1.Actually the best solution was

http://blogs.microsoft.co.il/blogs/barbaro/archive/2008/12/01/creating-sum-for-a-group-with-recursion-in-ssrs.aspx

I was missing that second column(in the article called "Total Order Quantity") which solved my SSRS aggregation issue.

2.But the sql in itself also worked....

Thanks, that has worked