Ugh, never mind. That sucks. You might try some of the other things I mentioned. I had high hopes for using two gaskets.
These are not Grolsch - I have some of those. They are store bought new flippies with ceramic caps and they did not carbonate. I think I had 1 or 2 out of 24 that carbonated.
My bet would be that it is the bottles. I just opened two more of the store bought flippies, and one was pretty well carbed, and the other was flat. We got two OK glasses by mixing them half-and-half in mugs, so we both got semi-flat beer.
I made some home-made gaskets out of thicker silicone, and they seem to hold pressure. I tested them with baking soda and vinegar, and they don't seem to leak (tested in a plastic bag), and they give a good "pop" when I opened them. I think I'm also going to try bending some of the wires that seem suspect, since some need more force to close than others. Wish me luck on my next bottling!