Most people that have been in brewing very long seem to agree that a common problem is low pitch rates. I have taken to dividing out each tube into approximately six starters, each time that i'm go to brew, I take approximately a sixth of a tube and make a 1000ml starter. This takes approximately a weeks time. So far I have been very successful all starters have had very healthy fermentation cycles, most start within 6 to 8 hrs. In this way I defray the cost of yeast and frankly it makes my hobby a lot more fun, learning to manipulate the yeast!!!!