I have a Powerpoint template that contains 1 slide and on that slide is a chart. I'd like to be able to manipulate that charts data using .NET. So far I have code that... unzips the Powerpoint file. unzips the embedded excel file (ppt\embeddings\Microsoft_Office_Excel_Worksheet1.xlsx) It successfully manipulates the data in the excel sheet and zips it back up. Opens and manipulates ppt\charts\chart1.xml Powerpoint is then zipped up and delivered to the user The result of this is a Powerpoint file that shows a blank chart. But when I click on the chart and go to edit data it updates the data and shows the correct chart. I believe my problem is with the chart1.xml that I am generating. I have compared my generated version with a version created by Powerpoint and they are almost identical. The only differences are in the values for <c:crossAx> and <c:axId>. There are also some rounding difference in the data. But I do not feel like that would result in an blank chart. Is there another file that I need to edit? Does anyone have any ideas as to what else I should try to get this working?