Why is it that whenever I don't try, I pick up girls easy, but when I try, I get cold shouldered?

Whenever I go out and I'm not making an effort I can pick up girls really easily like I'm Ryan Gosling or some shit, but when I do make an effort nothing happens and I get rejected? Can anyone help me here, like I have no problem with approach or talking, but if I'm think I wanna get wit her nothing happens.