adding items to a listbox in a groupbox with radiobuttons vb 2008

Hi,
I have a groupbox containing 3 listbox and 3 radio buttons, Im trying to write a function to add items to all 3 listbox, but I keep getting errors like Conversion from type 'RadioButton' to type 'String' is not valid type errors, is there a way to specify which control on the groupbox I want to work with?

Function ListBoxDefault(ByVal intSelected As Integer) As Integer
 
        For Each ctrl As ListBox In Me.GroupBox2.Controls
 
            ctrl.Items.Add(CStr("wwwww"))
             ctrl.Items.Add cstr("dddddd
        Next
 
    End Function
 
OR this
 
 
For Each listbox As String In Me.GroupBox2.Controls
            listbox.Insert(0, "wwww")
 
            
      Next
End Function

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