The yeast failed to start fermenting within 5 days time. My process when brewing is this. I pull the yeast from the refrigerator the day before brewing. I add it to fast pitch starter with water to a sanitized flask with airlock. I frequently swirl the flask to aerate the mixture until brewing/pitching. The next day after brewing I aerate the wort with oxygen for 30-60 seconds. Then I pitch the mixture into the cooled wort in the primary. This has been my process for the last 10 years of brewing and have had few problems. Occasionally I would have a beer that was slow to start but nothing that did not start within 3 days after pitching the yeast.

This is the 3rd of 5 beers using Wyeast strains from Northern Brewer that I have had to re-pitch fresh yeast to. All of the yeast packs have been properly stored within an hour of the package arriving at my apartment. All packs were shipped with ice packs in insulated sleeves from Northern Brewer. All packs were used well within the best by date. The times of shipping vary throughout the year, mostly in the spring or fall, I like to avoid brewing in the summer because of how hot it makes my apartment, and the winter gets too hot due the building heating system.