Linked data in a chart
 

Excel 2007
I have a chart (bar) showing regional sales results.
Inside of that chartI want to give additional explanations eg the total
sales of all regions.

So I thought: use a linked picture.

Unfortunately the option of "linked picture" is not available when the chart
is highlighted.
In Excel2003 I would have built the information in linked textboxes and
grouped them with the chart.
But with 2007 I can't group anything with the chart other than by
highlighting the chart and then pasting the stuff.
When I create a linked picture outside of the chart and then (link)-paste it
into the chart, the link is lost.

So I'm stuck.

How can I get linked information (picture, textbox, ...) on top of a chart?

Thanks for your help (on this and on previous questions).
Michael