Expression for Growth/Decline bar chart?

[#1]

I need to make a bar chart that would simply have a bar for each month showing % growth or decline versus the previous month. So some bars should go negative, some positive.

I achieved a similar effect in a table using the expression:

RangeSum(sum([SALES]),-Before(sum([SALES])))/Before(sum([SALES]))

along with a date dimension.

This expression however does not display data in a bar chart for some reason, even though it says expression OK and I use the same dimension....

Thanks in advance.

[Gysbert_Wassenaar]

See attached example. Is that what you're looking for?