B4J Question Type with a list in it give java error

[Marc De Loose]

Type xRotateKnobsCollectionType (BackdropName As String, lst_xRotateKnobs As List, Active As Boolean)

When I run it line 4 (xRotateKnobCollection.lst_xRotateKnobs.Initialize) throws an error.
Can someone correct what I am doing wrong?

    ' TEST TEST
                Private xRotateKnobCollection As xRotateKnobsCollectionType
                xRotateKnobCollection.BackdropName       = imgName
                xRotateKnobCollection.lst_xRotateKnobs.Initialize
                xRotateKnobCollection.lst_xRotateKnobs.AddAll(lst_xRotateKnobs)
                All_lst_xRotateKnobs.Add(xRotateKnobCollection)

 

[LucaMs]

xRotateKnobCollection.Initialize