求助：TList排序问题

type
  TBat = record
    v1: Integer;
    v2: Integer;
    v3: Integer;
  end;
  PBat = ^TBat;

function SortValue(p1,p2: PBat): Integer;
begin
  result:=CompareValue(p2.v1,p1.v1);
  if result = 0 then
    result:=CompareValue(p2.v2,p1.v2);
  if result = 0 then
    result:=CompareValue(p2.v3,p1.v3);
end;

procedure TForm1.FormClick(Sender: TObject);
var
  i,j: Integer;
  list: TList;
  bat: PBat;
begin
  list:=TList.Create;
  try
    randomize;
    for i:=0 to 2 do
    for j:=0 to 3 do
    begin
      new(bat);
      bat.v1:=i*10;
      bat.v2:=(j div 2)*20;
      bat.v3:=random(20);
      list.Add(bat);
    end;
    list.Sort(@SortValue);
    self.Repaint;
    for i:=0 to list.Count-1 do
    begin
      bat:=list[i];
      canvas.TextOut(20, 20*(i+1), inttostr(bat.v1));
      canvas.TextOut(50, 20*(i+1), inttostr(bat.v2));
      canvas.TextOut(80, 20*(i+1), inttostr(bat.v3));
    end;
  finally
    for i:=0 to list.Count-1 do
      dispose(list[i]);
    list.Free;
  end;
end;