changing a code

hi all, is there any way changing the "ActiveWorkbook.UpdateLink" to "ActiveSheet.UpdateLink"? This command must be wrong, it gives error. How can I correct this? This is to update links only on a particular sheet (active one) rather then updating the whole workbook.
Thanks


Sub update()
'
' update Macro
'

'
ActiveWorkbook.UpdateLink Name:= _
"C:\Documents and Settings\Alper\Desktop\Excel\source.xls", Type _
:=xlExcelLinks
End Sub