I brewed an amber ale (Fat Tire tribute) on Friday night. Because my yeast was a bit older (4 months old), I gave it 2.5 days to activate before pitching. Per the recipe instructions, I waited until the wort was at 80 degrees, then I added the yeast. I became concerned when, by Sunday, there were still no bubbles in the air lock. So, I went to my local supply store and inquired. They said that the particular yeast does better around 70 degrees or less. So I bought some new yeast, activated it, and pitched it that night. It is now Tuesday and still no bubbles in the air lock. I have accepted the fact that this batch is a bust. However, I'd love to understand what I may have done wrong before brewing another batch. Any ideas?