Ordenar ListView

function ByFourth(Item1, Item2: TListItem; Data: integer):
integer; stdcall;
var
n1, n2: String;
begin
n1 := Item1.SubItems[Column];
n2 := Item2.SubItems[Column];
if n1 > n2 then
Result := -1
else if n1 < n2 then
Result := 1
else
Result := 0;
end;

begin
if (Column > 0) then
ListViewMensagem.CustomSort(@ByFourth, 0) //Ordena as demais colunas
else
ListViewMensagem.SortType := stText; //ordena a 1ª coluna
end;