请教高手！一个程序错误，忘能给出解释！谢谢

Question

var
    ThreadList:TList;
procedure TForm2.BtnTestThreadClick(Sender:TObject);
  begin
    if ThreadList.LockList.Count<=0 then
      begin
        try
          MyThread:=TTestThread.Create(False);
          ThreadList.Add(Self);
        except
          MyThread.Terminate;
      end;
  end;
  MyThread.Priority:=tpNormal;
  MyThread.CtrlEdit[0]:=Edit1 as TEdit;
  MyThread.CtrlEdit[1]:=Edit2 as TEdit;
end;
procedure TTestThread.Execute;
begin
  try
    ...
  finally
    Synchronize(CtrlEditEnabled);
    ThreadList.Clear;//有时候单步执行到这里就无法执行下去
    with ThreadList.LockList do
    begin
      try
        Pack;
        Count:=0;
      finally
        ThreadList.UnlockList; 
      end;
    end;
  end;
end;
谢谢各位大哥大姐了，这个错误我怎么都不理解！
希望能给出个详细点的解释啊！

Answer 1

MyThread.CtrlEdit[0]:=Edit1 as TEdit;
  MyThread.CtrlEdit[1]:=Edit2 as TEdit;