Hi Jon,

I would try another procedu Link the chart with a named
range, e.g.

..Chart.SetSourceData Source:=Sheets("NameGoesHere").Range
("arguments")

Then you can name the arguments range, starting at a known
cell e.g. A2 and down all filled rows with:

..Range("A2", "A" & .Range("A2", "A65534").SpecialCells
(xlCellTypeBlanks).Cells(1).Row - 1).Name = "data"

For info: xlCellTypeBlanks gives you the first empty cell,
therefore you need to use .Row - 1


Best

Markus