I too think you over-diluted it. You don't dilute the dilution. As Anikin said, mix 20ml part A in 500ml of water, mix 20ml part B in 500 ml water, and then mix the two together to get a liter of working solution.
Also, what paper are you using? Not all papers lith. What temperature are you using? Some papers need a higher temperature to appear (faster) -- 5 minutes as opposed to 30 minutes. I generally find that, however long it takes for the first image to appear, if you double the time, that should probably be close to the time it will take to lith properly (depending on the look you are going for of course).
Anyway, let us know if the new dilutions work for you (and with what paper).