How can I change the linked variable of an element during run time using VB.net macro. I have something like this

Private Sub zDynamicPicts_Open(ByVal obDynPicture As zenOn.IDynPicture) Handles zDynamicPicts.Open
' MsgBox(CStr(obDynPicture.Name))

If obDynPicture.Name = "PopupScreen1" Then
If lVar = "b1" Then
For i As Integer = 0 To obDynPicture.Elements.Count - 1
If obDynPicture.Elements.Item(i).Name = "Numerical value_1" Then
obDynPicture.Elements.Item(i).set_DynProperties("variable", Me.Variables.Item("dnptest1"))
End If
End If
End If
End Sub

My currently linked variable to the element is "test1". I want to replace it with "dnptest1"