求助！！！关于对象关闭时不允许操作的解决方法

HAkunamaTt~

  本人菜鸟一只，学与编同时进行，请大神们看下面代码：
Public Sub ReadDatabase()
    Dim layer As AcadLayer
Dim util As New clsLayerUtility
If Not util.NewLayer("里程标", layer) Then
MsgBox "创建图层失败"
End If
Dim color As New AcadAcCmColor
color.ColorIndex = acWhite
layer.TrueColor = color
util.SetCurrentLayer ("里程标")
    Dim con As New ADODB.Connection
    con.Open "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & GetCurrentDvbFilePath() & "Database\point.mdb"
   
    Dim rstPoly As New ADODB.Recordset
    rstPoly.Open "Select [PolylineID] From Polyline", con, adOpenDynamic, adLockOptimistic
    While Not rstPoly.EOF
      
        Dim rstVerts As New ADODB.Recordset
        Dim sql As String
        sql = "Select [里程]From Point Where [PointID] In (Select [PointID] From PolylinePoint Where PolylineID = " & CStr(rstPoly.Fields(0)) & ")"
        rstVerts.Open sql, con, adOpenDynamic, adLockOptimistic
        
     
   
     
     
     
     
        Dim verts As New cls2dPointArray
        Dim vert(0 To 1) As Double
        Dim a As Single, j As Single
        a = CDbl(rstVerts.Fields("里程")) - 910
        While Not rstVerts.EOF
            SetPoint2d vert, CDbl(rstVerts.Fields("里程")) - a, 245
            j = CDbl(rstVerts.Fields("里程"))
            verts.Append vert
            
            rstVerts.MoveNext
        Wend
        
        
        
        
        
        
        
        rstVerts.Close
        
        Dim mspace As New clsModelSpace
        mspace.AddLWPolyline verts.toarray()
        
        rstPoly.MoveNext
    Wend
   
   
   
   
   
    '画竖线
    Dim i As Single, k As Single
   
   
    k = j - a
    For i = 910 To k Step 10
Dim lcbz As AcadLine
       Dim lcbzsp(0 To 2) As Double, lcbzep(0 To 2) As Double
   
    SetPoint3d lcbzsp, i, 245, 0
       SetPoint3d lcbzep, i, 244, 0
    Set lcbz = ThisDrawing.ModelSpace.AddLine(lcbzsp, lcbzep)
        Next i
  
  
  
    ' 写数字
    Dim lcbx(0 To 2) As Double, lcby(0 To 2) As Double
    Dim kongge As String, m As Integer, biaozhu As String
    If Not rstVerts.EOF Then
    If j Mod 1000 = 0 Then
    m = Int(j / 1000)
    ElseIf j Mod 100 = 0 Then
    m = Int((j - Int(j / 1000) * 1000) / 100)
    biaozhu = m
    End If
   
    kongge = "      "
SetPoint3d lcbx, 910, 242, 0
SetPoint3d lcby, k, 244, 0
mspace.AddTextInRectangle lcbx, lcby, biaozhu & kongge
  rstVerts.MoveNext
    End If


   
   
   
    rstPoly.Close
        con.Close

End Sub
这个画里程标注的代码，为了标注里程数字，我加了红色部分，但是一直提示对象关闭时不允许操作，怎么解决呢？