You have it almost right. Wilson's trip to Niger did convince him that Saddam was trying to obtain yellow cake and he told the CIA that when he returned. This was an oral debriefing. Later Wilson wrote this big op-ed article about there being no attempt by Iraq to obtain uranium. A Senate committee later found unanimously that Wilson lied in his op-ed, that he did orally report that he found paydirt in Niger. But the media routinely ignores this established fact. Very frustrating. The American MSM is simply not reliable anymore. Makes room for the blogosphere and pajamhadeen.
Joe was very careful when he talked about the yellow cake. He said that there was none issued through legal purchase channels and if they did get any, it was obtained illegally. In other words, who knows?