Problem adding Series XValues to Chart using VBA
 

I have an intermittent and vexing problem trying to add new series to a Chart
using Excel 2002 VBA.

Here's a snippet:

For i = 1 To NumSeries
DataCol = ChartData(k).SeriesParam(i).DataCol
Set rgY = Sheets("Appointment
Efficiency").Range(ActiveSheet.Cells(StartRow, DataCol),
ActiveSheet.Cells(ActiveRow, DataCol))
Set rgX = Sheets("Appointment
Efficiency").Range(ActiveSheet.Cells(StartRow, 2),
ActiveSheet.Cells(ActiveRow, 2))

scSeries.NewSeries
scSeries(i).XValues = rgX
scSeries(i).Values = rgY
scSeries(i).Name = ChartData(k).SeriesParam(i).SeriesName

This crashes with a Runtime Error : "Method 'XValues' of Object 'Series'
failed" *most* of the time. Sometimes it runs fine. When it crashes, Excel
hangs and I have to kill it.

I have tried all variants of the range object for the X values, including
just typing a static range for testing. A little more background - the chart
already exists, and I delete existing series from it before adding the new
ones back. The YValues add fine if I just comment out the XValues line.
Everything else works great - point labels, line types, etc all set using VBA.

Any help/suggestions would be much appreciated.

Thanks,

Sean