Kinda like the "reliable tip" GWB got that Saddam still had WMDs.
Such tips do not always reflect reality.
Just because they have not been found does not make the information wrong or a lie. Obviously you have not heard about Iraqi general Georges Sada saying that they hauled them out to Syria, by planes and trucks, prior to our invasion.
GWB was not the only one that had the "reliable tip", Chirac warned that if we invaded that Saddam would use his WMDs. The British had the same information. Also, there were the Migs that were hidden under sand that were modified to distribute WMDs in spray form.