removing items of a listbox dinamically

Hi there,
I have a windows form that has a listbox that on a event it loads items to it.  After user do something or change the tab or screen and comes back to the screen I have a line of code that reads as follows:

 If rlcExportPrevious.Items.Count > 0 Then
                        rlcExportPrevious.Items.Clear()
End If

Select allOpen in new window

after the second time around where there is data on the listbox I get an error saying "Object reference not set to an instance of an object." so in my effort to trying to solve the issue I have added a loop to remove items like this:

   While rlcExportPrevious.Items.Count > 0
                            rlcExportPrevious.Items.RemoveAt(rlcExportPrevious.Items.Count - 1)
   End While

Select allOpen in new window

this works until I get to the last record and throws the same error. If I use the word new as it suggests I lose the event SelectedIndexChanged and I need to keep that functionality. How do I solve my issue?
Thanks for your input