Problem With Short-pass


I'm working with the Equipment: (short-pass, vacuum, controller vacuum and circulator) and want to start my fractionate distillation on raw oil. I switch on the vacuum, controll the stability of it and go as high as i can with it (1 kPa). Then i start raising gradually the temperature slowly (i have a probe Inside the liquid to controll the temperature).
I have to go to 250 C* to have ebulltion, even higher to have my first oil fraction, and i don't understand why. Furthermore, i afraid to degrade the cannabionoïd.

I really need your help on this because i tried to change all the parameter and it doesn't seem to affect the process. Can you help me?