Hi - I'm new to the Master-Cleanse also, but from what I've read so far it sounds like you'll need to add more salt. I know it sounds contradictory, but it works. I added a 3rd tsp this morning and let me tell you there was a definite difference!
Some of the more experienced fasters use even more salt than that. I would just increase it until it works.
Laying down on your right side after you drink it helps too. (about 30 minutes, but I think even a few minutes would help)
Are you using a laxative herbal tea at night too? that helps as well because it gets everything loosened up and ready to be flushed out, so to speak.