either 1- source material doesnt have enough dmt
or 2-dmt is there in the solvent, but its not saturated enough to precipitate
3-dmt is in the solvent, but its spread through the glass and you dont realize that adding all up together when you scrape, it will be a proper amount (is it first time you do it? first time SWIM did it, he thought somethign went wrong, not enough crystals, but when scraping all up and putting together it did give the propper amount, just didnt look like)
4-pH not high enough
option 2 and 3 you can eliminate/confirm by evaping more of it, leaving small amount of solvent, making it a supersaturated solution (its never too much) and then sticking in the fridge, so I would try that first
option 4 can be confirmed/eliminated if you still have the mix there, and you add more caustic soda and then do another couple of pulls...
if neither of these options are confirmed, then probably its option 1..
if you explain the process its easier to spot where a possible problem might be..
was it STB or A/B extraction? Do you know if the source material is trustable? How much caustic soda/water/rootbark did you use? Normally when SWIM makes extraction, he puts enough caustic soda to get jet black, but AFAIK really dark brown should be enough to turn most dmt into freebase..