rdlc与子报表和对象类

I'm using Microsoft Reports (rdlc), and I need to create report with subreport. As a data source I created two Object Classes, PositionObject and PositionSubElementObject. PositionObject is data source for the main report, and PositionSubElementObject is a data source for the subreport. When I run this two reports separately, everything is ok, but when I create report with subreport, I'm gettin error in subreport.I'm using Microsoft Reports (rdlc), and I need