Crystal Reports Bar Chart: Display with filtered data

Message

   I have a set of data, and would like to have different bar chart on different category.

Is there any way to filter the data at bar chart level?

My report design as below:

Grouping by DocNo
For example, 3 rows of group header:
DocNo:0001     Time:50seconds   Category:A
DocNo:0002     Time:15 seconds  Category:A
DocNo:0003     Time:40 seconds  Category:B

I hide the details section as this is the section to analysis data and display at group header. Category A / B is defined based on the data at details section.

For first bar chart (y axis=Time, x axis=doc no), I would like to display data with Category A only. But I unable add grouping by category as this is define while report running at details section.
Any idea how to filter the data (only category A) and display in Bar Chart?

Edited by crstar - 18 Sep 2012 at 9:32pm