[LISP程序]：一段打印新开图纸的代码 - 请高手指点哪里出错了

lotsnow

假如打开了autocad，当前图纸为drawing1.dwg, 现在想写一段代码让它打开d:\test\drawing3.dwg并且用PDF995打印机把它打印成PDF, 代码如下，但是打印出来的总是drawing1, 而不是想要的drawing3, 请个位高手斧正。谢谢！
(defun c:go ()
  (setq AcadObject (vlax-get-acad-object))
  (setq    ActiveDocument
     (vla-get-ActiveDocument AcadObject)
  )
  (setq AcadDocuments (vla-get-documents AcadObject))
  (setq    AcadDocument
     (vla-open AcadDocuments
           "d:\\test\\drawing3.dwg"
     )
  )
  (vla-put-activedocument  AcadObject  AcadDocument)

  (vla-plottodevice
    (vla-get-plot
      AcadDocument
    )
    "PDF995"
  )

  (vla-close AcadDocument :vlax-false)
  (vlax-release-object AcadDocument)
  (vlax-release-object AcadObject)
)