Android Question cursustekst.be B4A-List Tutorial | Null Pointer Exception

Private mnuitem As B4AMenuItem = B4XPages.AddMenuItem(objpage, itemname)

Sub Class_Globals
    Private Root As B4XView
    Private xui As XUI
    Private catpage As CategoryPage
    Private subcatpage As SubcategoryPage
End Sub

Public Sub Initialize
'    B4XPages.GetManager.LogEvents = True
catpage.Initialize
subcatpage.Initialize
B4XPages.AddPage("Category", catpage)
B4XPages.AddPage("Subcategory", subcatpage)
menuitem_Add(Me, "Category")
menuitem_Add(Me, "Subcategory")
End Sub

Private Sub menuitem_Add(objpage As Object, itemname As String)
    Private mnuitem As B4AMenuItem = B4XPages.AddMenuItem(objpage, itemname) 'This throws exception
    mnuitem.AddToBar = True
End Sub

Sub B4XPage_MenuClick(Tag As String)
    B4XPages.ShowPage(Tag)
End Sub
'This event will be called once, before the page becomes visible.
Private Sub B4XPage_Created (Root1 As B4XView)
    Root = Root1
    Root.LoadLayout("MainPage")
End Sub