I brewed an ale. The krausen never really took off. Maybe one quarter of an inch. It's been five days. Can I just add more yeast? Homebrewing

I had waited a little bit too long to make this recipe, and the yeast sat in my refrigerator for about three weeks. I feel like it should still be okay, but apparently it is not. The fermentation is not happening. It has been sitting there for about five days, can I just throw more yeast in? or will that affect the brew adversely?

Submitted December 16, 2014 at 04:22AM by spdorsey http://ift.tt/1zYYrVl Homebrewing