I believe what Kay said was in reponse to a question that asked if Iraq had any LARGE stockpiles of WMD, to which he reponded, "No."
From there the press took "no LARGE stockpiles" to mean Iraq had no WMD at all.
I have read the Kay Report and what I gather from it is this.... Saddam was aware of how easy it would be to get caught producing large amounts of Chemical and Biological Weapons for stockpiling them, and the risk of having them discovered and destroyed. I believe he buried the existing stockpiles in Iraq, or shipped them to Syria for burial, as he kept all the Scientist and Laboratories necessary to quickly produce those weapons on a moments notice. The Kay report details this conclusion quite graphically IMHO.
But the Kay report does not explain what happened to the unaccounted for WMD's pre 1998. and I've already posted my belief on where they are