用OleContainer控制Word问题

Question

定义
Ole: TOleContainer;procedure TFrmSetWordRep.Button1Click(Sender: TObject);
begin   //打开Word文件
  try
    Ole.CreateObjectFromFile('C:\S.doc',True);
  except
  end;
end;
procedure TFrmSetWordRep.OleActivate(Sender: TObject);
begin  //替换文档中[UnitName]为：单位名称
  Ole.Modified:=True;  Ole.OleObject.Application.CommandBars['Standard'].Visible:=True;
  Ole.OleObject.Application.CommandBars['Formatting'].Visible:=True;
  Ole.OleObject.Application.CommandBars['Reviewing'].Visible:=False;
  Ole.OleObject.Application.CommandBars['Drawing'].Visible:=False;  Ole.OleObject.Application.Selection.Find.Text:='[UnitName]';
  Ole.OleObject.Application.Selection.Find.Replacement.Text:='单位名称';
  Ole.OleObject.Application.Selection.Find.Execute;
end;在执行Ole.OleObject.Application.Selection.Find.Text:='[UnitName]';代码是发生下面的错误：
Access violation at address 00000000.Read of address 00000000 那位能帮我分析一下代码阿