Usando DBChart

Nao sei se ajuda... mas eu uso o Chart e nao o DbChart

veja o codigo q uso para mostrar as vendas mes a mes em um periodo selecionado

procedure TFormPrincipal.Vendas_datas_Sel;
var

dia1, dia2,mes2,ano2, i, mes1, ano1 : word;
Nd1, Nd2 : TTreeNode;
tot: currency;
data1,data2: TDateTime;
dias: extended;
meses: integer;

Application.CreateForm(TFormSenha, FormSenha);
 formsenha.ShowModal;
 if formsenha.Permissao=true then begin
 entradatas1.Data1:=now-365;
 entradatas1.Data2:=now;
 if entradatas1.Execute then begin
 decodedate(Entradatas1.Data2,Ano2,Mes2,Dia2);
 decodedate(entradatas1.data1,ano1,mes1,dia1);
 with ibquery2 do
 begin
 sql.Clear;
 Sql.Add('select mes_b ,SUM(vendasprincipal.totalvenda) as valor');
 SQL.Add('from meses, vendasprincipal');
 Sql.Add('where (EXTRACT( MONTH FROM datapedido))=:mes and (extract(year from datapedido))=:ano');
 Sql.Add(' and concluida=' + quotedStr('S'));
 sql.Add('group by mes_b');
 end;
 GrafVendas.TreeView1.Items.Clear;
 grafVendas.Chart1.Series[0].Clear;
 tot:=0;
 data1:=encodedate(ano1,mes1,10);
 data2:=encodedate(ano2,mes2,LastDayOfMonth(mes2,ano2));
 for i:= 0 to MonthsBetween(data2,data1) do begin
 ibquery2.Close;
 decodedate(data1,ano1,mes1,dia1);
 ibquery2.ParamByName('mes').asinteger:=mes1;
 ibquery2.ParamByName('ano').asinteger:=ano1;
 ibquery2.Open;
 tot:=tot+ibquery2.fieldbyname('valor').ascurrency;
 with GrafVendas.treeView1.Items do begin
 nd1:=add(nil,LongMonthName(data1)+'/'+inttostr(ano1));
 AddChild(nd1,formatfloat('#,###,##0.00',ibquery2.FieldByName('valor').ascurrency));
 end;
 GrafVendas.Chart1.Series[0].Add(ibquery2.FieldByName('valor').ascurrency,shortmonthname(data1)+#13+inttostr(ano1));//ShortMonthName(data1));
 if mes1 in [1..11] then
 mes1:=mes1+1
 else if mes1=12 then begin
 mes1:=1;
 ano1:=ano1+1;
 end;
 data1:=encodedate(ano1,mes1,05);
 end;
 end;
 with grafvendas.TreeView1.Items do begin
 nd1:=add(nil,'Total No Periodo');
 addChild(nd1,formatfloat('#,###,##0.00',tot));
 end;
 GrafVendas.Caption:='Vendas Periodo Selecionado ';
 GrafVendas.showmodal;

Atencao('Não Permitido Sem Autorização');
end;
FormSenha.Release;

Joarez