在使用RAVE报表中打印teechart图表报错？(50分)

想在RAVE报表中显示曲线，试了一下网上的例子（“在Rave报表中打印TeeChart图表”
）： http://www.5iask.com/info/2006-7/374.htm
预览时，提示 field DataView1ieChart. Datatype expected:dtString Datatype found:dtGraphic.
我将dtGraphic 改为dtstring后，依旧提示类型不对。
能否指点一下，谢谢！

具体程序如下：
procedure TForm1.FormCreate(Sender: TObject);
begin
Series1.FillSamplevalues(50);
end;

procedure TForm1.RvCustomConnection1GetRow(
Connection: TRvCustomConnection);
begin
WriteChartData(Connection, Chart1);
end;

procedure TForm1.RvCustomConnection1GetCols(
Connection: TRvCustomConnection);
begin
with Connectiondo
begin
// PieChart is the name of the DataField that you will use in Rave
WriteField('PieChart', dtstring, 30, '', '');
//dtGraphic
end;
{ with }
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
RvProject1.execute;
end;

procedure TForm1.RvCustomConnection1Open(Connection: TRvCustomConnection);
begin
ChartRow:= 1;
end;

procedure TForm1.RvCustomConnection1Next(Connection: TRvCustomConnection);
begin
inc(ChartRow);
end;

procedure TForm1.RvCustomConnection1EOF(Connection: TRvCustomConnection;
var Eof: Boolean);
begin
Eof := (ChartRow > 1);
end;