Has anyone ever tried using number as a listitem key?

You can't do it!

Even if the number is a string it complains.

Code:
Private Sub Command1_Click()
Dim itmx As ListItem
Dim strKey  As String
strKey = CStr(22222)

Set itmx = ListView1.ListItems.Add(, strKey, "Item 1")
End Sub
Is there a way around this?