我这个旋转Text结果怎么不对?

plaer

    foreach(ObjectId id in btr)
    {
     Entity ent = (Entity)myT.GetObject(id,OpenMode.ForWrite);
     if(ent.GetType() == typeof(Text))
     {
      Text et=(Text)ent;
      et.Rotation=45.0;
      //Autodesk.AutoCAD.Geometry.Matrix3d m3d =new Matrix3d();
      //m3d.SetToRotation(2,new Vector3d(0,0,0),ent.Position);
      //ent.TransformBy(m3d);
      et.RecordGraphicsModified(true);
     }
    }

运行过后没有反应。。怎么回事？？谢谢！