How To Sort ListBox In Ascending Order

I have 2 listbox (List1 and List2). List2 get populated when the user select a value in List1 and based on the value selected in List1. My issues are:

1- Values in list2 are not sorted in ascending order especially when the list2 grows over 32.
2- When the user selects "None" in List1, it should clear List2 (onclick)

I worked on this code for a while with no luck trying to get it to work. Is that doable?

VB:

Option Explicit
Dim ufEventsDisabled As Boolean
Function SelectedString() As String
Const Delimiter As String = ","
Dim i As Long

[Code] .....