I've got the Redbacked Spider Eye, Frost Pygmy Shrunken Head, Desert Wolf Fang and Ectoplasm (lended to me) spoke to him and got nothing, I didn't have my Crystal Orb, Shards of Faces or my filled Vials - started that bit just to pass time - though, perhaps I'll go try with the other items but I'm doubting it will work.
Oh I didn't talk to Semeneth though, I don't think it's required to complete the riddle quest specifically but meh... I'll try it.