在visualbasic中对autocad进行二次开发碰到的问题！(急)

lcj68

在visualbasic中编程，碰到了一个问题：运行到类似Set boxobj = acadApp.ActiveDocument.ModelSpace.AddBox(boxcenter, boxlength, boxwidth, boxheight)的语句，就会出现：
       实时错误‘424’
       要求对象
       结束（E）      调试（D）         帮助（H）

因为没有安装msdn，所以就不知道问题出在哪里了 ！请好心的您解决我这个问题吧！！
不甚感激！！！

具体程序如下：
Private Sub Form_Load()
    On Error Resume Next
   
    '与AutoCAD通信
    Dim acadApp As AcadApplication
    Set acadApp = GetObject _
                  (, "AutoCAD.Application")
    If Err Then
        Err.Clear
        Set acadApp = CreateObject _
                  ("AutoCAD.Application")
        If Err Then
            MsgBox Err.Description
            Exit Sub
        End If
    End If
   
    '连接autocad，并使其画图
    Dim acadDoc As AcadDocument

    Set acadDoc = acadApp.ActiveDocument

   End Sub

Private Sub Command1_Click()
Dim boxobj As Acad3DSolid
Dim boxlength As Double, boxwidth As Double, boxheight As Double
Dim boxcenter(0 To 2) As Double
boxcenter(0) = 5#: boxcenter(1) = 5#: boxcenter(2) = 0
boxlength = 10#: boxwidth = 7: boxheight = 10#

Set boxobj = acadApp.ActiveDocument.ModelSpace.AddBox(boxcenter, boxlength, boxwidth, boxheight)
boxobj.Color = acBlue

Dim cylinderobj As Acad3DSolid
Dim cylindercenter(0 To 2) As Double
Dim cylinderradius As Double
Dim cylinderheight As Double
cylindercenter(0) = 0#: cylindercenter(1) = 0#: cylindercenter(2) = 0#
cylinderradius = 5#
cylinderheight = 20#

Set cylinderobj = acadApp.activedocement.ModelSpace.AddCylinder(cylindercenter, cylinderradius, cylinderheight)
cylinderobj.Color = acBlue

boxobj.Boolean acIntersection, cylinderobj
boxobj.Color = acRed

Dim newdirection(0 To 2) As Double
newdirection(0) = -1: newdirection(1) = -1: newdirection(2) = 1
acadApp.ActiveDocument.ActiveViewport.Direction = newdirection

acadApp.ActiveDocument.Preferences.ContourLinesPerSurface = 20
ZoomExtents
acadApp.ActiveDocument.Regen True

End Sub

mccad

Dim acadApp As AcadApplication
和
Dim acadDoc As AcadDocument
应该放到声明段，而不应该放到
Private Sub Form_Load()
内

lcj68