your code have a little mistake ,,
SetSelected(Index as integer, value as boolean)
index means like the number of the item
when u select valu1 which is eqaul to last item number it selectes the last item
so u will just have to do a simple loop
Code:ListBox1.SelectionMode = SelectionMode.MultiExtended For i = 0 To ListBox1.Items.Count - 1 ListBox1.SetSelected(i, True) Next