This column chart is based on 3 series, which are colored green, red, and grey. On the left column, there are no red values, and on the right value there are only grey. I don't want the chart to display the 0s.
I can imagine that there might be a time when I do want the zeros to show, though I'm not sure why (since you won't be able to see the color). Maybe if it weren't stacked, I'd want the 0s to show and the color would be implied by the relative positions as compared to other groups. If you don't want to just turn off the 0s, please add a 'display zeros' checkbox next to the 'show values' checkbox that is enabled when the 'show values' checkbox is checked.