Bike tire goo

I recently put slime filled inner tubes on my road bike - they're supposed to plug up holes as soon as they get punctured. On Monday I was riding home in the rain and heard the dreaded sound of "Pffttt sisssssssssssssssss" as a hole got made in my front tire. I looked down and saw the green slime shoot out and the hole stopped leaking. Amazing, it really worked. The next day I was riding to the rock gym and heard the same sound "Pfffffttt sisssss". Well, I have my trusty tube to plug the hole. I pulled over because it wasn't stopping. I looked at the hole on the top of the tire. No slime, no goo. After the tire went flat I remembered the instructions "When tire gets punctured, rotate tire until the hole is at the bottom." So the goo will fill the hole. I took the flat tube out and pumped it up to get the slime working. I held it upside down and everything. The hole was filled, but so was my valve, I couldn't add any more air. So you know, don't do what I did. Instead follow the directions. I guess they're there for a reason.