Hi,

you'll need to include the file name or the sheet name when you enter the range name for the series.

In the formula bar, make sure you see:

=SERIES(sheet1!$A$1,'FileName.xls'!LabelRangeName,'FileName.xls'!DataRangeName,1)

or in the Source Data dialog box make sure that the Values are defined like this:

='FileName.xls'!DataRangeName

and in the labels field:

='FileName.xls'!LabelRangeName


hth