Some seeds can take as long as 7-14 days to pop, I myself wouldnt wait longer than 7 days if that. I have a few seeds on hand though so i can afford to try a different one.
you might want to try LIGHTLY scraping the edges of the seed. I've heard people using knives, I just use my nails and it seems to work fine, may sure you wash your hands and under your nails REALLY well though.