Different varieties sprout at different rates, and even seeds of the same variety can sprout at different rates. Also, you could feasibly have some seeds that are not viable, such as from a pod that was not allowed to fully mature. Finally, sometimes "nasties" (mold, fungus, bacteria) can get to the seeds and activate when you add water. So could be fine, or maybe not. How long ago did you start them, have you kept them between 75-80 degrees, and what varieties?
Â
Also, don't let them dry out too much unless we come back and say it's probably been too long. For the "nasties", you can pre-soak seeds in a 10:1 mix of water and hydrogen peroxide to help kill off the nasties before you start  your "real" sprouting method. Don't need to soak more than 10-30 minutes, though some will say overnight - either is fine.