No, Don't give up. It can take a while for some seeds to sprout. Even from the same strain. It could be a bad seed but it may just have a tough shell and not willing to crack as of yet. If it looks like the seed is still sealed then soak it in a glass of water for 6-12 hours to let the water loosen the seed up then back into the moist paper towl. I say 6-12 hours because you have had it soaking for 4 days in a paper towl and you do not want to over do it. If it was from the start you would soak the seeds for 24 hours or so. Also try to keep it in a warm dark spot. The warm air will help it germ better. Keep trying and let us know how it goes.