Setworkpart In NX2306

I am trying to create an Assy with 2 Levels as shown below using nxjournaling.
(2 levels are just examples, there could be 4 or 5 levels, then the way to setworkpart as suggested by NX it will be complicated)
With Lv2, when I execute the setworkpart code using the method below, there is an error message "Attempted to set invalid part to be the work part"
Please help me correct the above error

For each iChild as component in Lv1.Getchildren()
'The condition to recognize iChild is Lv2
Dim partLoadStatus1 As NXOpen.PartLoadStatus = Nothing
theSession.Parts.SetWorkComponent(iChild , NXOpen.PartCollection.RefsetOption.Entire, NXOpen.PartCollection.WorkComponentOption.Visible, partLoadStatus1)
partLoadStatus1.Dispose()
next

(In NX 11 there is no such error)
I tried to record the degree using journaling to setworkpart for Lv2 and the code has the structure as below.

Imports System
Imports NXOpen

Module NXJournal
Sub Main (ByVal args() As String)

Dim theSession As NXOpen.Session = NXOpen.Session.GetSession()
Dim workPart As NXOpen.Part = theSession.Parts.Work

Dim displayPart As NXOpen.Part = theSession.Parts.Display

Dim markId1 As NXOpen.Session.UndoMarkId = Nothing
markId1 = theSession.SetUndoMark(NXOpen.Session.MarkVisibility.Visible, "Make Work Part")

Dim component1 As NXOpen.Assemblies.Component = CType(displayPart.ComponentAssembly.RootComponent.FindObject("COMPONENT @DB/Level 1 Part No/AA 1"), NXOpen.Assemblies.Component)

Dim component2 As NXOpen.Assemblies.Component = CType(component1.FindObject("COMPONENT @DB/Level 2 Part No/AA 1"), NXOpen.Assemblies.Component)

Dim partLoadStatus1 As NXOpen.PartLoadStatus = Nothing
theSession.Parts.SetWorkComponent(component2, NXOpen.PartCollection.RefsetOption.Entire, NXOpen.PartCollection.WorkComponentOption.Visible, partLoadStatus1)

partLoadStatus1.Dispose()
theSession.SetUndoMarkName(markId1, "Make Work Part")

End Sub
End Module