What am I doing wrong on this dating website?

I've been on okcupid for a while and I've only met up once in real life and gotten probably 6 or 7 phone numbers that went no where. I usually send out a bunch of generic messages (usually a compliment) and then get some replies which I respond to at the time or a little later. Usually the girl will make very little effort to talk or will stop talking after a couple responses when asking them more about themselves. I don't get it