Не работает length(s)

if (s[length(s)]='/') then Copy(s,1,Length(s)-1);

unit Unit1;
 
interface
 
uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;
 
type
  TForm1 = class(TForm)
    Memo1: TMemo;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
    procedure EndThreadWork(Sender: TObject);
  end;
 
  TMyThread = class(TThread)
    FThreadNumber: byte;
    FStartValue: integer;
    FEndValue: integer;
    FResult: integer;
  protected
    procedure Execute; override;
  end;
 
var
  Form1: TForm1;
  thrCount: byte;
  totalSumm: integer;
 
implementation
 
{$R *.dfm}
 
{ TMyThread }
 
procedure TMyThread.Execute;
var
  i: word;
begin
  FResult:= 0;
  for i:= FStartValue to FEndValue do
    FResult:= FResult + i;
end;
 
// ========================================================================================
 
procedure TForm1.Button1Click(Sender: TObject);
var
  i: byte;
  MyThread: TMyThread;
begin
  // START
  Memo1.Clear;
  thrCount:= 11;
  totalSumm:= 0;
  // create Threads
  for i:= 0 to Pred(thrCount) do
  begin
    MyThread:= TMyThread.Create(true);
    MyThread.FreeOnTerminate:= true;
    MyThread.OnTerminate:= EndThreadWork;
    MyThread.FThreadNumber:= i;    // для контроля
    MyThread.FStartValue:= i * 1000;
    MyThread.FEndValue:= i * 1000 + 999;
    MyThread.Start;
  end;
end;
 
// ========================================================================================
 
procedure TForm1.EndThreadWork(Sender: TObject);
var
  MyThread: TMyThread absolute Sender;
begin
  // очередной поток завершил работу. считывание результата
  Memo1.Lines.Add(Format('Поток %d завершил работу. Результат %d',[MyThread.FThreadNumber,MyThread.FResult]));
  totalSumm:= totalSumm + MyThread.FResult;
  Dec(thrCount);
  if thrCount = 0 then  // все потоки завершили работу
  begin
    Memo1.Lines.Add('=========================');
    Memo1.Lines.Add(Format('Total Summ: %d',[totalSumm]));
end;
 
end.

s:=StringReplace(s,'ht','',[rfReplaceAll]);

function test(s:string) :string;
begin
               s:=StringReplace(s,'ht','',[rfReplaceAll]);
end;

s:=StringReplace(s,'ht','',[rfReplaceAll]);

function test(s:string) :string;
begin
   Result:=StringReplace(s,'ht','',[rfReplaceAll]);
end;

function test(VAR s: string) :string;

RESULT:=StringReplace(s,'ht','',[rfReplaceAll]);

if ((Pos('body', link) > 0) and (s=''))
               then begin link:=nik+'body'+kik; end else
                    if ((Pos('body', link) > 0) and (s<>''))
                    then begin link:=nik+'nobody'+s; end;
 
if ((Pos('kody', link) > 0) and (s=''))
               then begin link:=nik+'kody'+kik; end else
                    if ((Pos('kody', link) > 0) and (s<>''))
                    then begin link:=nik+'nobody'+s; end;
 
if ((Pos('pody', link) > 0) and (s=''))
               then begin link:=nik+'pody'+kik; end else
                    if ((Pos('pody', link) > 0) and (s<>''))
                    then begin link:=nik+'nobody'+s; end;

function XXX(param:string):string;
begin
  result := 'yyyy';
end;

   procedure Button13Click(Sender: TObject);
    procedure Button14Click(Sender: TObject);
 
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
  type
  TMyThread = class (TThread)
  http: THTTPSend;
  StringList: TStringList;
  Data: TStringStream;
  private
    link,kik,nik: string;
    buf: string;

procedure TMyThread.Execute;
var
   s:string;

function linktest(var s,link,kik,tik:string) :string;
 
begin
if ((Pos('kody', link) > 0) and (s=''))
               then begin link:=nik+'kody'+kik; end else
                    if ((Pos('kody', link) > 0) and (s<>''))
                    then begin link:=nik+'nobody'+s; end;
 
if ((Pos('pody', link) > 0) and (s=''))
               then begin link:=nik+'pody'+kik; end else
                    if ((Pos('pody', link) > 0) and (s<>''))
                    then begin link:=nik+'nobody'+s; end;
result:=link;
end;

if pos(s[length(s)],'/')>0 then copy(s,1,Length(s)-1);

if pos(s[length(s)],'/')>0 then copy(s,1,Length(s)-1);

uses Sysutils;
 
s:=ExcludeTrailingPathDelimiter(s);

linktest1(link,s,kik,nik);
form1.label7.caption:= link;