Populate 2 custom Ribbon Dropdowns using only 1 callback function

[Luthius]

Guys
I added 2 dropdown controls on my custom ribbon.
DropDownCategory (dynamic)
DropDownSubCategory (dynamic)

Dynamic means that the list can increase as soon a new item is added.
I would like to create just one callback function to populate these 2 dropdowns.
I'm using getItemLabel="PopulateDropDown" for both in the xml syntax.

I tried the following code for my callback function but without success because it is only populating the first CASE of my SELECT CASE.
Can someone advise me please?

Sub PopulateDropDown(control As IRibbonControl, index As Integer, ByRef label)
    Dim ActiveCategory As Variant
    Dim ActiveSUBCategory As Variant
    ActiveCategory = GetCategories()
    ActiveSubCategory = GetSUBCategories()
    Select Case control.ID
        Case "DropDownCategory "
            label = ActiveCategory (index)
        Case "DropDownSubCategory "
            label = ActiveSUBCategory (index) + 1
    End Select
End Sub