acidophilus and homemade yogurt

Hi

I've been making homemade yogurt for quite some time now and as a starter, I usually use some yogurt from the previous batch and toss in the contents of an acidophilus capsule.

As an experiment the other day, I used ONLY the contents of an acidophilus cap (that I keep in the fridge and also just recently purchased).

It did not ferment the milk. I did not get yogurt.

So - does this mean that the "live" cultures in my acidophilus are deader than a doornail?

Thanks for your input - w