CompConfigProperties4 giving error

Hi
I am getting the error when i am setting the componentconfiguration in the assembly.Whether Part1 has three configurationas Conf1,Conf2 and Default

Dim swApp As Object
Dim Part As Object
Dim SelMgr As Object
Dim boolstatus As Boolean
Dim longstatus As Long, longwarnings As Long
Dim Feature As Object
Sub main()

Set swApp = Application.SldWorks

Set Part = swApp.ActiveDoc
Set SelMgr = Part.SelectionManager
boolstatus = Part.Extension.SelectByID2("Part1-1@Assem1","COMPONENT", 0, 0, 0, False, 0, Nothing, 0)
'Part.CompConfigProperties4 2, 0, True, "Conf1", False
Part.CompConfigProperties4 2, 0, True, "Conf2", False
Part.ClearSelection2 True
boolstatus = Part.EditRebuild3
End Sub

Thanks in advance
Regards
Anil
Solidworks 2008 SP 4.0
SolidworksApi macros