There is an issue concerning in sub-reports.

I created a bar chart in report header. The sub report(inline) is placed in the Details of main report. In the sub report, the bar chart is placed in the group header. I imported the required parameters to the sub reports from the main report and also i have a sub query for the sub report.The expected output is to show an updated bar chart within each (inner) group of main report. However, the chart is only displayed in the last group occurence, although the chart area itself is allotted in every expected case. Can any one say me, what mistake i did.