Thanks Hilary,
Thanks for that sample you provided, I managed to get it to work to a limited degree. Unfortunately when i converted the Subtotal Amount field to a calculated value, i got an error advising me that the control binding is not supported and allow me to upload it to the sharepoint.
I attempted to upload the template but when i try to run it from sharepoint it crashes. It seems to be isolated to this bug. If i remove the summary fields and reupload it without the error it goes back to normal and works