You may not be inhaling slowly enough. Since you're passing hot air over the bud, if you pull too quickly, you may not be getting the THC oil hot enough to boil and vaporize. Try pulling very slowly. I've found with my vaporizer I can get it too hot and it will actually hurt more than smoking. Obviously if you do it right, it won't hurt nearly as much as smoking though. I've had people who claim they don't get high off vaporizers and I attribute it to a mixture of bias (yeah smoking hurts so it muuust be the best way) and high tolerance (the ones who claim vapes don't work smoke a hell of a lot and thus will not feel anything special when hitting a vape). They're simply healthier. Sometimes they get you higher, sometimes not. Its no different from smoking regularly. Some days you will get very high, some days not because of set/setting, tolerance, mood, bud quality, etc.