series w/ named range not shown when reopen chart
 

My workbook has two sheets: the data on "Sheet4" and a chart sheet
"Chart1" that refers to data on "Sheet4". The chart has three
series. Two series use absolute cell references, one uses a named
range which defines a dynamic block of data (cells containing data
from L7 down), so the range name is defined as =OFFSET(Sheet4!$L
$7,0,0,COUNTA(Sheet4!$L7:$L65536),1).

The chart works just fine, until I save and close the workbook and
then try to reopen it. When I reopen, the chart doesn't show the
series defined with the named range. If I look at the source data for
the chart, the series is still defined appropriately, etc. It is as
if Excel has "forgotten" about that series or can't figure out what it
is.

Can anyone help? Is there some way of "reminding" excel what to do
when I reopen the workbook?

TIA,
Mike