Need help with Delphi coding.

[Necrobat]

I'm making a Connect 4 game for a school assignment, and my code should work in theory, but in reality it doesn't. Whenever I run the game, the board tries to draw itself, but then fails to do so. Can anyone please give me any advice? Thanks in advance.

unit Unit2;
interface
uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls;
const
 
  nbrcols=7; 
  nbrrows=6; 
  sidewidth:integer=10; 
  player1color:TColor=clred;  
  player2color:TColor=clyellow;  
  boardcolor:TColor=clblue; 
  lookahead:integer=4; 
type
  TFormGame = class(TForm)
    BtnExitGame: TButton;
    PnlGame: TPanel;
    Image1: TImage;
    NewChip: TShape;
    BtnNew: TButton;
    BtnRetract: TButton;
    procedure TokenMouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure TokenMouseMove(Sender: TObject; Shift: TShiftState; X,
      Y: Integer);
    procedure TokenMouseUp(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure BtnExitGameClick(Sender: TObject);
    procedure BtnNewClick(Sender: TObject);
    procedure BtnRetractClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
    board:array [1..nbrcols, 1..nbrrows]of integer; 
    moves:array[1..nbrcols*nbrrows] of TPoint;     player1:boolean; 
    chipwidth:integer; 
    Dragchip:boolean;  
    movecount:integer;  
    gameover:boolean;  
    procedure initialize;
    Procedure DrawChip(x:integer);
    procedure DropChip(x:integer);
    function FourInARow(col,row:integer):boolean; 
    function match(col,row,dc,dr:integer):integer;  
    procedure changeplayers;
  end;
var
  FormGame: TFormGame;
implementation
uses Unit1;
{$R *.dfm}

procedure tFormGame.initialize;

       procedure DrawNewBoard;
      
      var
        i,hinc:integer;
      begin
        with image1, canvas do
        begin
          chipwidth:=(PnlGame.width-(nbrcols+1)*sidewidth) div nbrcols;
          PnlGame.width:=nbrcols*(chipwidth+sidewidth)+sidewidth+2;
          PnlGame.height:=(nbrrows+1)*chipwidth+sidewidth+2;
          picture.bitmap.width:=width; 
          picture.bitmap.height:=height;
          brush.color:=clwindow;
          fillrect(clientrect);
          brush.color:=boardcolor; pen.color:=boardcolor;
          rectangle(rect(0,height-sidewidth,width,height));
          hinc:=(width-10) div nbrcols;
          for i:= 0 to nbrcols do rectangle(rect(i*hinc,chipwidth, i*hinc+sidewidth,height-sidewidth));
        end;
        newchip.width:=chipwidth;
        newchip.height:=chipwidth;
        drawchip(chipwidth div 2);
       end;{Drawnewboard}
var i,j:integer;
begin
  for i:=1 to nbrcols do  for j:=1 to nbrrows do  board[i,j]:=0;
  movecount:=0;
  player1:=false;
  changeplayers; 
  drawnewboard;
  tag:=1;
  gameover:=false;
end;
procedure TFormGame.BtnRetractClick(Sender: TObject);
var
  h,v:integer;
begin
  if movecount>0 then
  begin
    with image1.canvas, moves[movecount]  do
    begin
      board[x,y]:=0;
      brush.color:=clwindow;
      h:=sidewidth+(x-1)*(chipwidth+sidewidth);
      v:=y*chipwidth;
      fillrect(rect(h,v, h+chipwidth, v+chipwidth));
    end;
    dec(movecount);
    changeplayers;
    drawchip(chipwidth div 2);
  end;
end;

procedure TFormGame.BtnNewClick(Sender: TObject);
begin
Initialize;
end;


procedure TFormGame.Changeplayers;
begin
  newchip.top:=0;
  player1:=not player1;
  if player1 then
  begin
    newchip.brush.color:=player1color;
  end
  else
  begin
    newchip.brush.color:=player2color;
  end;
end;

procedure TFormGame.drawchip(x:integer);
begin
  newchip.left:=x-chipwidth div 2;
  newchip.visible:=true;
end;

function TFormGame.match(col,row,dc,dr:integer):integer;
var c,r,count, checkplayer:integer;
begin
  checkplayer:=board[col,row];
  c:=col+dc;
  r:=row+dr;
  count:=0;
  while (c>=1) and (c<=nbrcols) and (r>=1) and (r<=nbrrows) and
         (board[c,r]=checkplayer) do
  begin
    inc(c,dc); inc(r,dr);
    inc(count);
  end;
  result:=count;
end;

function TFormGame.FourInARow(col,row:integer):boolean;
{Chck for 4 tokens in a row}
var  n:integer;
begin
  n:=1+match(col,row,-1,0)+match(col,row,+1,0);
  if n<4 then n:=1+match(col,row,0,-1)+match(col,row,0,+1);
  if n<4 then n:=1+match(col,row,-1,-1)+match(col,row,+1,+1);
  if n<4 then n:=1+match(col,row,-1,+1)+match(col,row,+1,-1);
  if n>=4 then result:=true else result:=false;
end;

procedure TFormGame.dropchip(x:integer);
var
  col, row, i:integer;
  msg:string;
begin
  col:=x div(chipwidth+sidewidth)+1 ;
  newchip.left:=sidewidth+(col-1)*(chipwidth+sidewidth);
  row:=1;
  while (row<=nbrrows) and (board[col,row]=0)
  do inc(row);
  if row=1 then exit;
  dec(row);
  with newchip do
  for i:=1 to row+1 do
  begin
    top:=(i-1)*chipwidth;
    update;
    sleep(100);
  end;
  if player1 then board[col,row]:=1
  else board[col,row]:=2;
  with image1.canvas do
  begin
    brush.color:=newchip.brush.color;
    with newchip do ellipse(left,top, left+width, top+height);
  end;
  inc(movecount);
  moves[movecount]:=point(col,row);  if (movecount=nbrcols*nbrrows) or fourinarow(col,row) then
  begin
    if fourinarow(col,row) then
      if player1 then msg:='Player 1 is the winner!'
      else msg:='Player 2 is the winner!'
    else msg:='A draw!';
    Gameover:=true;
    newchip.visible:=false;
  end;
end;
procedure TFormGame.TokenMouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  if gameover then exit;
  DragChip:=true;
  newchip.top:=0;
  drawchip(newchip.left+x);
end;
procedure TFormGame.TokenMouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
begin
  if dragchip
  then drawchip(newchip.left+x);
end;
procedure TFormGame.TokenMouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  if board[(newchip.left+x) div (chipwidth+sidewidth)+1,1]<>0 then
  begin
    newchip.left:=0;
    exit;
  end;
  dropchip(newchip.left+x);
  dragchip:=false;
  if not gameover then
  begin
    changeplayers;
    drawchip(chipwidth div 2);
  end
  else
  begin
    newchip.top:=0;
    player1:=not player1;
    if player1 then newchip.brush.color:=player1color
    else newchip.brush.color:=player2color;
  end;

end;
procedure TFormGame.BtnExitGameClick(Sender: TObject);
begin
  FormGame.close;
  FormMain.show;
end;
 
end.