Suddenly (!!) my charts won't update when I change the data it refers to. So,
even if I clear the entire column it refers to, the line (and old data) stays
present in the chart. It does show the right column in "source data" (even
shows it empty!), but keeps remembering the "line", even when I re-select it!
This way, I can not update my data!
I didn't change any settings, and it's not with all charts within one
workbook.

What's going on? I've been working with excel for a long time but I have
never had anything like this!! Please help!