Hello Steve,
The "Excel Report" interface only provides a small subset of the full Excel functionality. It's intended to be an easy-to-use interface for basic functionality. For something more advanced, such as what you want to do now, you'll have to use the lower-level C interface, which is a direct wrapper of the original Excel interface.
The good news is that you can easily combine the two interfaces. You'll notice that whenever you use excelreport.fp in a program, the "Microsoft Excel 9.0 Object Library" instrument also gets loaded automatically by CVI. What you have to do in your case is to use a couple of functions from that instrument. The code below should do it (assuming you are changing the point size for the
first series in the chart):
Excel_ChartSeriesCollection (chartHandle, NULL, CA_VariantInt(1), &seriesHandle);
Excel_SetProperty (seriesHandle, NULL, Excel_PointMarkerSize, CAVT_LONG, 2);
Good luck!
Luis