Graphs don't update automatically
As one PowerPoint newsgroup visitor put it:
"I have a presentation in MS PowerPoint 97. It includes several graphs created in PowerPoint; each graph's datasheet is linked to an Excel file. When the Excel file is revised, the various graphs in PowerPoint must reflect these changes. Even though I set up the links as "Update: Automatic", I find that when I open the PP presentation, it doesn't always show the latest data from Excel. However, once I open & close the graphs in PP, they'll show the correct data."
To understand why this happens, you first have to know that PowerPoint itself doesn't make graphs.
Instead, it fires up MSGraph, an "applet" whose sole purpose in life is to supply graphs to PowerPoint and other applications via OLE (Object Linking and Embedding).
For automatic updating to occur, PowerPoint needs to check the date of the data source of any embedded OLE objects, and for this to happen, it needs to be able to find the file that contains the original data to see if the file date/time is more recent than the date/time on the embedded copy in the PPT file.
Here's where you run into the first problem: MSGraph doesn't save any data to files. It passes its data back to the app that called it and slinks away into the night. No saved data in a file, nothing to trigger PowerPoint's automatic link updates. The only way to force an update is to get PowerPoint to hand the embedded data back to MSGraph and edit it there. In other words, doubleclick the graph or write VBA code that does it for you.
The fact that Excel supplied the data in the first place doesn't really enter into things. The link is from MSGraph to Excel in this case, but MSGraph is never launched until you doubleclick the graph in PowerPoint, so only then does it realize that there's a link to external data and update it from Excel.
To solve the problem, you could create the graphs in Excel in the first place, then Paste Link them to PowerPoint, leaving MSGraph entirely out of the picture.
Or you could download this add-in from PowerPoint MVP Shyam Pillai to resolve the issue.
1. Load the add-in
2. Open the presentation with the graphs to be updated.
3. Select Tools | Update charts and your charts will be updated.
If you cannot load an add-in in PPT2000/XP. Then check the macro settings (Tools | Macros | Security), if set to a security level - HIGH, this would prevent any unsigned add-in from being loaded. To resolve this...
1. Select Tools | Macros | Security on the security level tab, check MEDIUM.
2. Click on OK
3. Now load the Add-in as per the instructions.
4. Once the add-in has been loaded you can set the Security level back to HIGH