Well... it can be done, but the result is nasty. The hash oil you can get from this is weak, and full of all the bad substances (many of them are carcinogenic) that exist in the resin of burnt weed. And it tastes awful too. Sincerely, i dont recommend it. If you want make hash oil, make it from weed, kief or trim, cause the resulting product is WAYY more enjoyable.
"Everything we do, everything we are, rests on our personal power. If we have enough of it, one word uttered to us might be sufficient to change the course of our lives. But if we don't have enough personal power, the most magnificent piece of wisdom can be revealed to us and that revelation won't make a damn bit of difference." Don Juan Matus - Tales of Power