Промежуток между датами в StringGrid

procedure TForm2.Button4Click(Sender: TObject);
var
i:Integer;
begin
  for i:=1 to 50 do
StringGrid1.Cells[2,i]:=(IntToStr(YearsBetween((StrToDateTime(Edt22.Text)),(StrToDateTime(StringGrid1.Cells[1,i])))));
end;

for i:=1 to 10 do

StringGrid1.RowCount := StringGrid1.RowCount + 1;

if not StringGrid1.Cells[1, i].IsEmpty then ...

   if not StringGrid1.Cells[1,i]:=('') then
          Exit;

for i:=1 to 50 do
 if not StringGrid1.Cells[1, i].IsEmpty 
  then StringGrid1.Cells[2,i]:=(IntToStr(YearsBetween((StrToDateTime(Edt22.Text)),(StrToDateTime(StringGrid1.Cells[1,i])))));

if not StringGrid1.Cells[1, i].IsEmpty

var
  i: integer;
  dt: TDateTime;
begin
  for i := 1 to 50 do
    if TryStrToDateTime(StringGrid1.Cells[1, i], dt) then
      StringGrid1.Cells[2, i] := IntToStr(YearsBetween(StrToDateTime(edt22.Text), dt));
end;

StringGrid1.Cells[2, i] := IntToStr(YearsBetween(Today, dt));

procedure TForm1.StringGrid1SetEditText(Sender: TObject; ACol, ARow: Integer;
  const Value: string);
var
  grid: TStringGrid;
  dt: TDateTime;
begin
  grid := Sender as TStringGrid;
 
  if grid.EditorMode then
    Exit;
  if ACol = 1 then
  begin
    if TryStrToDateTime(Value, dt) then
      grid.Cells[2, ARow] := IntToStr(YearsBetween(Today, dt));
  end;
end;