Hey man check out this link
http://www.poolsolutions.com/kit/ps2...gent_life.html

it shows that the pH reagent can deteriorate in sun or heat.

Being a fellow Louisianian I am familiar with our heat and humidity. I would bet that you are correct in saying that the reagent went bad since it was sitting outside in our wonderful climate.

Can you keep your stuff inside? All of my pool testing equipment and reagents stay inside to keep them as "fresh" as possible.