SELF and SENDER problem

Dear Experts,

I have a procedure called: Connect1Click(Sender: TObject);
That procedure is called often in the procedure below:

procedure Tscreenf.New1Click(Sender: TObject);
begin
  if IsModified then
  begin
    case MessageDlg('Do you want to save the current file?', mtConfirmation,
      [mbYes, mbNo, mbCancel], 0) of
      mrYes:
        begin
          Save1Click(Sender);
          if SocOpen then Warning1
          else begin
            LoadOptions(CfgFile);
            CurrentFile := CfgFile;
            Connect1Click(sender);           <--------------------
          end;
        end;
      mrNo:
        begin
          if SocOpen then Warning1
          else begin
            LoadOptions(CfgFile);
            CurrentFile := CfgFile;
            Connect1Click(sender);        <--------------------
          end;
        end;
      mrCancel: ;
    end;
  end
  else
    if socOpen then Warning1
    else begin
      LoadOptions(CfgFile);
      CurrentFile := CfgFile;
      Connect1Click(sender);      <--------------------
    end;
end;

But when I want to call for procedure Connect1Click(Sender: TObject);
in the procedure below:

begin
  if (Application.MessageBox(PChar('You must disconnect host ' +
    ConnectHostName + ' before opening another connection.' + #10 + #13 +
    'Do you want to disconnect?'),
    'Access2All',
    MB_YESNO + MB_DEFBUTTON1 + MB_ICONEXCLAMATION) = ID_YES) then
  begin
    Disconnect;
    LoadOptions(CfgFile);
    CurrentFile := CfgFile;
    Connect1Click(self);                    <-----------------
  end;
end;

i get an error:    [Error] Main.pas(375): Undeclared identifier: 'sender'
When I use SELF instead of SENDER it works, what's the diffirence?

greetings,

Peter Kiers