nothing certain.. I believe it was the temperature of my wash when fermenting, as I used bread yeast.
I raised the temperature to about 20 C and was able to get it down to 1.011 gravity, I distilled it at that, I don't know the quality yet, I bottled it with wood chips to try to mellow it, so i will see what it's like in a couple months.
I really don't think I'm the one to ask, sorry.. it could be what they said above. although my wash had no molasses at all and fermented down to 1.011 although it did take about 40 days...