He may have simply stopped when you didn't give him a scantily clad picture. But keep in mind...
Getting the girl a little interested and then completely ignoring them is a common tactic guys use. It makes girls who are insecure with themselves think "what's wrong with me?" or "what did I do wrong to make him ignore me?" Then when they finally meet up again, the situation has changed from the guy trying to attract the girls interest, to the insecure girl trying to attract his interest, thereby making her more pliable to his advances.
It doesn't work with self-confident women, but it's like shooting fish in a barrel with women who have low self-esteem.
I've never done this, and I hate guys who do, but it's a pretty common thing for guys who are experienced at seducing women.