The proper way to access the listbox control would be:
However, there is a known issue, related to ListBox, when it is data-bound in PanelBar if the PanelBar is in OtlookNavPane mode. In this case, the panel bar adds the child ContentPanel controls to its child Controls collection only when the corresponding item (PanelBarGroupElement) is selected. Then, RadListBox would not behave correctly and will not create its items, despite that its datasource is assigned. The solution to this problem would be to assign BindingContext of the Form to the ListBox before setting the DataSource:
lst.BindingContext = Me.BindingContext
lst.DataSource = ...
Let me know if you need assistance any further.
the Telerik team