Only do SWF (Salt-Water-Flush) on empty bowels (or if you know that what is in you is minimal).
My experience with SWF's is such that, I too, occasionally had no elimination with one quart. Two things I did. I drink at least 2 glasses of water an hour before my SW, then I drink a second quart of SW an hour after the first. You NEED to be hydrated before taking that first quart of SW. And, within that second hour, I have always had several eliminations.
I sometimes precede the first quart with a 2 quart SW enema