Can you attach some workbook to help you?
The problem is that most of the built-in diverging color palettes go from one color to another meeting at white or grey in the middle, but you can create your own custom palette that does not do this. Here's how: Create Custom Color Palettes
I created the following palette that goes from black to a bright red:
<color-palette name="Black/Red Diverging" type="ordered-diverging" >
Using superstore, I dropped Profit on the Color card, then chose this palette:
However, it still shows a range of colors (not all negatives are black), so I created a calculated field as follows:
IF SUM([Profit])<0 THEN
I then dragged this to the color card and chose the palette:
Close, but one of the problems with this is that low values still show very black. If you want postitive values to be more red, then you can fiddle with the color palette settings. For example, here I've selected "Use Full Color Range" and set the Center at 500:
See attached workbook.
Diverging.twbx 2.3 MB