Many of the recipes, and instructions that come with the PR, call for rehydrating 24 hours prior to use. I never found it necessary but never tried it either. Many of them call for rehydration in cool water 10 minutes prior to use. I usually rehydrate it in cool water when I place the milk in the pot and begin heating, about an hour before use but that is with the powder. I have also just placed the powdered form onto the milk at the beginning of the heating phase. They all worked fine. I suspect his PR is the issue. It doesn't sound like he may have used enough and I would like to know which one he used. As I'm sure you are aware, different PR cultures call for varying amounts.