Hmmm...it shouldn't be "rolled" at all. You use the end of a tweezers or a blunt toothpick to center the piece of PTB and then pull it down over the stick. If you pull it out of the cart, it should look like a closed umbrella without the handle.
Are you using a whole piece of PTB? It should only be a half of the tea bag. Each PTB bag should yield 2 carts.
Are you using a whole piece of PTB? It should only be a half of the tea bag. Each PTB bag should yield 2 carts.