Teemo No Life Steal or Spell vamp

While playing teemo, I have tried using some life steal and spell vamp items and found that they do not work. I never received health from regular attacks (which with teemo also applies AP poison) thus I also didn't receive spell vamp from regular attacks or spells like blind or the shrooms. I think it may be an issue with the fact that the damage is a combo of the two and the items arnt set up to read duel damage for spell vamp and life steal. But id think that with an item like the hextech gunblade that it would be able to read the duel damage because it does regular life steal and spell vamp but I've tried that as well and it does not work. I'm hoping someone will look into this and fix this bug so I can play more affectively with teemo.