A bit late, but maybe it will be useful for someone else. When in the reportviewer there is a jump to other report (detail report) you need to add the DataSource for the detail report. You can do this easily by implementing the event method 'Drillthrough'. Go to the events of your reportViewer instance, create the method, and add a code like this:
private void reportViewer1_Drillthrough(object sender, DrillthroughEventArgs e)
{
Microsoft.Reporting.WinForms.ReportDataSource dataSrc = new Microsoft.Reporting.WinForms.ReportDataSource();
dataSrc.Name = "DataSet1";
dataSrc.Value = this.DataTable1BindingSource;
LocalReport localReport = (LocalReport)e.Report;
localReport.DataSources.Add(dataSrc);
}
Please notice that the data source is being added to the report of the event parameter 'e'. Not to the local report of the your reportViewer