添加所有多段线图形到一个集合出错

Private Sub SelectLots(ByVal Ssetname As String, _
    ByVal objName As String, _
    Optional strPrompt As String = "请选择单行文本，可以框选" & vbCrLf)
    'Ssetname 新建选择集的名
   'objName 要选择对象的名，可以文字对象，也可以是直线或其它任何acad实体
   'strPrompt 选择时提示的文字
    Dim sSetObj As AcadSelectionSet, flag As Boolean
    For Each sSetObj In ThisDrawing.SelectionSets
        If sSetObj.name = Ssetname Then
            flag = True
            Exit For
        End If
    Next
    If flag Then sSetObj.Delete                                                 '创建集合，如集存在，则删除，新建
    Set sSetObj = ThisDrawing.SelectionSets.Add(Ssetname)
    Dim gpCode(0)    As Integer
    Dim dataValue(0) As Variant
    gpCode(0) = 0
    dataValue(0) = objName
    Dim groupCode As Variant, dataCode As Variant
    groupCode = gpCode
    dataCode = dataValue
    ThisDrawing.Utility.Prompt strPrompt
    sSetObj.SelectOnScreen groupCode, dataCode
End Sub
Sub kk()
Dim myset As AcadSelectionSet
Dim obj As AcadObject
SelectLots "drawletter", "*POLYLINE"
Set myset = ThisDrawing.SelectionSets("drawletter")
if  myset.Count=0 then exit sub
  For Each obj In myset
    Debug.Print obj.ObjectName
  Next obj
  myset.Item(0).Highlight True
End Sub