In the screen shot (where the chart does not look correct), are you referring to the white background, or are those bars above part of the screen shot.
If you are referring to the white background, then that would be what is expected.
However, if bars above are showing in the graph, then that looks like it is an issue. and in that case, please send me your file where the chart is shown along with the Dynamic Web Chart folder so i can debug the issue.