Originally Posted by arch1tect
In the future you could make up a tiny bit of wort and culture it in the bottle first. Then if you can confirm viability, step it up until you have enough for a good culture.
In my experience harvesting pacman, I had to step it up several times before having enough viable yeast to pitch into my beer. I started by using Malta (a nasty tasting unfermented beer drink, but a wonderful product to use for harvesting commercial yeast strains) to grow the first bit over a few days, then decanting the liquid off the yeast and doing it again. Finally I made a DME wort starter and grew the last bit.
By the time I was ready to brew I had over an inch of yeast in my jar.
Basically if the sediment is growing, you have viable yeast. You just need to coerce it to breed.
For your situation, it may have been too small amount of yeast to pitch. I believe (correct me if I am wrong), that it could still ferment properly, but its going to take sometime for the yeast to multiply enough to be able to tackle the massive amount of sugar available. I have read that under pitching can lead to stressed out yeast and off flavours, but I have no first hand experience with that/
And about airlocks; I don't trust them. Mine almost never bubble but I can see physical signs of fermentation (carbonation appearing, krausen, hydrometer readings
). I would take a reading and see if the SG has dropped any.