Ошибка "Error: Wrong number of parameters specified for call to "FloatToStrF""

unit Unit1;
 
{$mode objfpc}{$H+}
 
interface
 
uses
  Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls;
 
type
 
  { TForm1 }
 
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Edit1: TEdit;
    Edit2: TEdit;
    Edit3: TEdit;
    Edit4: TEdit;
    Label1: TLabel;
    Label2: TLabel;
    procedure Button1Click(Sender: TObject);
  private
    { private declarations }
  public
    { public declarations }
  end;
 
var
  Form1: TForm1;
  a, b, c, d, max: real;
  i: byte;
implementation
 
{$R *.lfm}
 
{ TForm1 }
 
procedure TForm1.Button1Click(Sender: TObject);
begin
  form1.height:=height+165;
  a:=strtofloat(edit1.text);
  b:=strtofloat(edit2.text);
  c:=strtofloat(edit3.text);
  d:=strtofloat(edit4.text);
  if a>b then max:=a else max:=b;
  if b>c then max:=b else max:=c;
  if c>d then max:=c else max:=d;
  if d>a then max:=a else max:=a;
  label2.caption:=FloatToStrF(max,ffFixed,5000);
  label2.Visible:=true;
end;
 
end.