Modifying a chart in powerpoint manually

I have a .net 2.0 application running in IIS, I need to create a single PPTX file containing a chart which I will have to edit dynamically.

I thought the easiest way is to edit the pptx file manually, however editing the inner xlsx file manually does not show the proper data when opening it in powerpoint.(Perhaps the data is cached somewhere in the file.)

I tried editing the xml documents inside the pptx file and the data was showed with 开发者_如何转开发no flaw.

Can anybody help me with this issue, all i need is some simple modifications.

It turns out I need to modify the file: /ppt/charts/chart1.xml, some of the values are cached there.

Note: there is a thumbnail image which i didn't modify, but i bet any of the users notice this.