Fórum Coalesce ... Naum consigo fazer funcionar em alguns computad #56400

procedure TForm3.Button1Click(Sender: TObject);
var
vsaldo : double;
begin
vsaldo:= 0;
//-------------------------calculos soma de saldos-----------------------------------
aguardedadoson;
with dm.calculos do
  begin
    close;
    sql.clear;
    sql.add(´select mes, ano, dataextenso, conta, sum(coalesce(valord,0))as debito, sum(coalesce(valorc,0))as credito, (sum(coalesce(valord,0)) - SUM(coalesce(valorc,0)))as saldo from tbconta´);
    sql.add(´WHERE (conta = ´ + quotedstr(Edit1.Text) + ´) and (ano = ´ + quotedStr(ComboBox1.Text) + ´)´);
    sql.add(´group by mes, ano, dataextenso, conta´);
    sql.add(´order by mes´);
    open;
    dm.calculos.First;

    while not dm.calculos.Eof do
    begin
      vsaldo:=dm.calculos.fieldbyname(´saldo´).asFloat+vsaldo;
      dm.calculos.FieldByName(´mes´).asString:=dm.calculos.fieldbyname(´mes´).asString;
      dm.calculos.FieldByName(´ano´).asString:=dm.calculos.fieldbyname(´ano´).asString;
      dm.calculos.FieldByName(´debito´).asFloat:=dm.calculos.FieldByName(´debito´).AsFloat;
      dm.calculos.FieldByName(´credito´).asFloat:=dm.calculos.FieldByName(´credito´).AsFloat;
      dm.calculos.FieldByName(´saldo´).asFloat:=vsaldo;
      dm.calculos.Next;
    end;
  end;
//-----------------------------------final codigo soma de calculo-------------------------------  
  //------------soma totaldebitos---------------
  with dm.somad do
  begin
    close;
    sql.clear;
    sql.add(´select sum(coalesce(valord,0))as totdebito from tbconta´);
    sql.add(´WHERE (conta = ´ + quotedstr(Edit1.Text) + ´) and (ano = ´ + quotedStr(ComboBox1.Text) + ´)´);
    open;
  end;
  //---------------------final soma debito------------
  //------------soma totalcredito---------------
  with dm.somac do
  begin
    close;
    sql.clear;
    sql.add(´select sum(coalesce(valorc,0))as totcredito from tbconta´);
    sql.add(´WHERE (conta = ´ + quotedstr(Edit1.Text) + ´) and (ano = ´ + quotedStr(ComboBox1.Text) + ´)´);
    open;
  end;
  //---------------------final soma credito------------
  if DM.calculos.isempty then
     showmessage(´Nao há registro neste numero de conta. Por favor tente novamente´);
     aguardedadosoff;
end;