Its seed coat is hard and thick, you have to grind off the tip (germination point) a bit before soaking in water, this will ease and speed up the germination.
3 r0 l' x+ R4 Q( Q- u
If you mean those from chinese groceries store, it may not be possible to germinate, I guess they are dried and the protective seed coat was peeled off. They are lifeless food stuff.