From my own shaman (110), looks like there are 33 ranks of Malaise. Rank 33 is for the 106-110 range, so rank 32 is for 101-105. I assume your shaman has Malosenete (102) in its spell book. From my spell list, it looks like Fetid Decay skipped the 101-105 range, so it should be using the 96 spell. Do you have both spells? The aa spells get messed up if you don't have the base spell you are expecting for the level of aa you have.