If all else fails, use the paper towel method so you can see what is going on and avoid issues with too much/too little water.
Soak the seeds overnight and then place them on dampened paper towel and seal in a zip-lock bag. Place somewhere warmish and keep an eye on them. If any signs of mold show up, remove the seeds, clean in a very dilute bleach or peroxide solution and return to a fresh bag/towel environment. Remove seeds as roots appear and carefully pot up.
When I have more than a few seeds I generally also plant a few in a mix of peat, perlite and vermiculite (4:2:1) or some other mixture with good drainage.
You just never know. I had ten precious p. antioquiensis seeds awhile back and sprouted a few each way. Eventually each resulting plant succumbed to something or another. In disgust and despair I put the remaining potted seeds outdoors in a semi-shady spot. Months after planting, one of the seeds has sprouted and is looking good :-) My last chance!
Q