Heat Pack not heating up?

Fed-Ex is coming in about an hour to pick up my package and it's been about 10 mins, and I've shaking and kneading but it's not doing anything.

http://www.uniheatproducts.com/directions.html

30 to 45 min to start to heat.

With our experience:

40hrs: Takes 1hr to generate good heat under a towel
60 and 72hrs: Around 2-3hrs

We always activate the packs hours before the FedEx driver pickup window. This is so we're not putting in cold packs in the box not knowing if they're even functioning or not..

-Sam

Good to know!