Access to a series, when it is assigned to an empty range
 

Hello,

I'd like to get access to a chart series via vba.
This works fine with
ActiveChart.SeriesCollection(1).Values =
"='" & ActiveWorkbook.Name & "'!" &
Diagramm1.Range("Chart1_Series1").Value
this is a reference to a named range.
So, if I assign the series to a range with values I can change the
series to another range afterwards.
But if I once have assigned a series to an empty range I do not have
access to the chart series any more.
The error message is:"unable to set the values property of the series
object"
Only manually it's possible to reactivate this series, then I can
continue to run vba

Does anyone have a workaround?

Excel XP SP 3
Windows XP SP 3

Regards
Werner