More Userform Listbox

I have a listbox that is populated based on a named range from another workbook. Below is the code that populates it:


Private Sub UserForm_Initialize()

Dim InvDB As Workbook

Set InvDB = Workbooks.Open("C:Documents and SettingsPATSYSDesktopInvoiceDB.xls")

With InvDB

ListBox1.RowSource = .Name & "!rng"

.Close

End With

End Sub
My problem.

When I scrollbar down, no data appears.

This leads me to think that I need some kind of userform event to keep populating the listbox (similar to my code above) as I scroll up or down.

My questions:
1. Is it possible to specificy a rowsource in the properties window for the listbox that is pointing to an external workbook? If so, how do I write the rowsource?

I know that if the source workbook is open, I can use the rowsource:

InvoiceDB.xls!rng

But if source workbook is close, the below does not work:

C:Documents and SettingsPATSYSDesktopInvoiceDB.xls!rng

2. What is the userform event when you click the listbox scrollbar up or down?