Почему не проходит компиляцию? выдает ошибку

unit Unit1;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, Grids, StdCtrls;
 
type
  TForm1 = class(TForm)
    Button1: TButton;
    Label1: TLabel;
    StringGrid1: TStringGrid;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
  mas: array [1..10, 1..5] of integer;
 
implementation
 
{$R *.dfm}
 
procedure TForm1.Button1Click(Sender: TObject);
 
var
i, j: byte;
min, max: integer;
begin
 
Form1.StringGrid1.ColCount := 10;
for i := 1 to 5 do
begin
min := maxint;
for j := 1 to 9 do
if mas[i, j] < min then
min := mas [i, j];
Form1.StringGrid1.Cells [9, i - 1] := IntToStr (min);
end;
 
//"ищем максимальное значение
max := -maxint;
for i := 1 to 4 do
if StrToInt (Form1.StringGrid1.Cells [9, i]) > max then
max := StrToInt (Form1.StringGrid1.Cells [9, i]);
// выводим на экран список оптимальных решений 
Form1.Label1.Caption := 'Оптимальное решение - ';
for i := 1 to 4 do
if StrToInt (Form1.StringGrid1.Cells [9, i]) = max then
Form1.Label1.Caption := Form1.Label1.Caption + IntToStr (i + 1) + ' ,';;
 Form1.Label1.Visible:=True;
end;
 
 
 
 
procedure TForm1.FormCreate(Sender: TObject);
 
var
i, j: byte;
x:array[1..600,1..600] of real;
begin
 
for i := 1 to 8 do
for j := 1 to 4 do
x[i,j]:=strtofloat(stringgrid1.cells[i,j]);
for i := 1 to 4 do
for j := 1 to 8 do
x [i + 1, j + 1] := strtofloat(Form1.StringGrid1.Cells [j, i]);
end;
 
 
procedure TForm1.Button2Click(Sender: TObject);
begin
StringGrid1.Visible:=True;
Button1.Visible:=True;
end;
 
end.