ChangeLink with remote file

Hi

Please can you help with this code:

Sub ChangeLink()
    Dim OldLink As String
    Dim NewLink As String
    Dim ws As Worksheet
    Set ws = ThisWorkbook.Worksheets("Sheet1")

    OldLink = "http://rate-bulletin-120308.xls"
    NewLink = "http://rate-bulletin-121008.xls"
    
    ThisWorkbook.ChangeLink Name:=OldLink, NewName:=NewLink, Type:=xlExcelLinks
End Sub

I want to set the Oldlink to be whatever is currently in use. There is only 1 link used within the workbook.

I have tried something like

OldLink = ActiveWorkbook.LinkSources(xlOLELinks)

but it doesn't work.

Many thanks for your help!