BIRT_Defects_Trend Graph Creation: Help needed in fetching

Hi,

I am creating a new report template. The main purpose of the template is to show the number of defects ( Work Items ) in a particular status.
And work Items of a particular category need to be fetched based on the values stored in custom categories added in my Project Area.

Which SNAPSHOT would help me fetch the details of Work Items along with the custom categories on it. The WORKITEMS_SNAPSHOT is not fetching the values needed.

Thanks,
_Shashank