Yes, I agree that the temp is the key...

Got this from another site, and works great for me...
The best vaporizer temperature for marijuana/THC vaporization is approximately 365° Fahrenheit, give or take 20° depending on the moisture content of the specific herbs you are using. Sometimes you may only need a lower temperature around 355° and sometimes you may need to go higher to about 375-385°, but again this depends on the herb. If you go above 385° you run the risk of heating the herb too much and it almost becomes like regular smoking because the vapor is so thick. If you go below 350° you run the risk of not vaporizing all the THC and wasting some of you marijuana.