I am using a large Excel 2002 workbook (circa 50k rows). When the worksheet
data is changed, the associated chart fails to update with the new data.
Instead, I have to manually make a change in the Source Data Range section of
the chart (any change will seemingly do - e.g deleting a number and retyping
it). This seems to re-establish the link with the worksheet data, and the
chart then updates. However, if the worksheet data is subsequently changed
again, the problem re-occurs.

The Charts were created using the normal Chart Wizard by highlighting the
relevant cell ranges. The ranges were not typed as I know that this can cause
updating problems.
While the workbook is large, the chart range only covers about 1000 rows.

I would appreciate any help in solving this problem.