hybrid pollination

[neophyte]

Hi, this question has probably been asked before, but I've been wondering why a lot of hybrid/cultivars can't produce seed pods. I don't have a lot of experience pollinating orchids, so maybe I just haven't given the orchids the correct conditions to create seed pods, but I've only managed to produce seeds with one phalaenopsis that had solid pink petals (ie., no patterns on petals, which seems to be more common in hybrids/cultivars). With any other of my orchids (I've only tried pollinating phalaenopsis), it just doesn't work. I noticed that those two flap thingies protecting the stigma are usually open but after you pollinate they close together to prevent other pollen sacs from pollinating the plant (which is cool), and usually when I try to pollinate my other orchids the flaps do close, but nothing beyond that happens -- the flower just aborts . Why does this happen?

edit: When I said pollination, I meant I took pollen from one flower of the plant and put it on the stigma of another flower on the same plant (or took pollen from one flower and put it on that flower's stigma)