Unable to Customize a "Pie" Business Graphics

I have created a WD Component and below the development details:

View : BG_CATEGORY
UI Element:
Business Graphics: BG

I selected chartType as "Pie" and now trying to customize the business graphics ui element. However, every time I start Chart Designer.
By default, the chartType in Chart Designer is "Columns". I don't understand how to resolve the issue.

XML file generated is: cd_bg_category_bg.xml ( I don't feel name is so long )

I tried searching a lot on google and SCN. However, Couldn't find any material on the same.
Any help/hint is appreciated.

Thanks,

Preetam