i am still very new to this, so my advice is not based on much experience at all, more what i have read around the internet and been told by people on forums. i am still halfway through my first ever extraction, but i have put a LOT of hours into learning (but still many more hours ahead of me!) just want to make that clear
300g in one extraction is a lot. i have read that the more you try to extract at once the lower percentage yield you typically get. its also recommended to learn with smaller amounts (usually 50g). it is common to get nothing from your first extraction or two, so learning on lower quantities saves on waste.
another thing i have read is that too much naphtha lowers yield. im not sure if this can get extreme enough to yield zero though. but it could be one of a few combined factors.
that said, i dont personally think thats too much naphtha. i am midway through my first ever tek right now and i used 75-100ml for 50g of MHRB and i have had a low yield for my first two pulls but i at least got something out.
the DMT will not evaporate with the naphtha, so even if you evaporated "too much" you would have still have the DMT in the naphtha. if you evaporated all of it then you would have been left with crystals if they were in there.
another common problem i have seen is freezers not being cold enough. i dont know what the temperature needs to be unfortunately, but if you have one of those freezers built into a fridge then that could be part of the problem.
its probably too late now. but you shouldnt have thrown anything away. the DMT could still be sitting in the bark, base or even the solvent and would still be retrievable. the only way that wasnt a waste is if the bark was dud.
your tek is very similar to the one i have been following, but my ratios are quite different. i have had a low first 2 pulls, my third is looking better so far, but i wont know for sure until tomorrow.
my ratios were, per 50g of bark, 50g of lye, 300ml of water (although i think that was too low and will be trying 400ml next with maybe another 10g of lye but i think the extra lye is not necessary) and 75-100ml of solvent (still playing with that number).
sorry i cant give you any definite answers, but hopefully that helps a little.