ERROR while adding summary field in group footer

Hi all,

i am using CR Server XI R2

i am trying to a subtotal in a group header using the code below

fieldobjCls = new CrystalDecisions.ReportAppServer.ReportDefModel.FieldObjectClass();

fieldobjCls.Kind = CrystalDecisions.ReportAppServer.ReportDefModel.CrReportObjectKindEnum.crReportObjectKindField;

fieldobjCls.FieldValueType = CrFieldValueTypeEnum.crFieldValueTypeInt32sField;

fieldobjCls.Name = "Count";

fieldobjCls.DataSource = "Count({CSP_PROCESS_REPORT.userid})";

fieldobjCls.Left = 1000;

fieldobjCls.Top = 700;

fieldobjCls.Width = 1000;

fieldobjCls.Height = 300;

boSection = rcDoc.ReportDefinition.get_GroupHeaderArea(0).Sections[0];

rcDoc.ReportDefController.ReportObjectController.Add(fieldobjCls, boSection, -1);

as a result i am getting the error as

Cannot find the section in the group area pair of the summary field.

how to solve

Padmanaban V