With the check valve you should be able to blow air easily in one direction but no in the other, If it is a clear valve the air flow should be in the direction of the taperd end of the valve inside.
As for the yeast, I would start over. Here is the recipe I use. I've tried a couple different ones and this is the best so far:
Make sure your bottle is clean. I just rinse mine with hot water each time I redo it.
Fill the bottle 2/3 full with warm water
Add 2 cups sugar and 1 tsp baking soda to the bottle and shake until completely disovled.
Take 1/2 cup very warm water and add 1/2 tsp yeast, stir briskly to disolve.
Let the yeast sit for 10-15 nimuntes to activate. (it will become really foamy)
Add the yeast mixture to the bottle (no need to mix) and within 24 hours your should see it starting to work. It will be slow at first but it will increase over the first couple days and should last about 3 weeks or so.
What size is your tank?