If the male is aggressively courting the female, but she is tail rattling and doing a little running away, she's probably not quite ready yet. I keep pairs together over-night to give the male enough time to fully court a female as sometimes, that's all it takes. If a female is stressfully running from an aggressively courting male, she may either be totally not ready, or has a great dislike for that male. A male usually won't aggressively court a female unless she is putting off lots of pheromones, meaning she is ready or close to it. In cases like that, I will try another male to see if the female still runs as much. Sometimes, a female just needs a different approach by a male as well. Some of my older breeder males will use different courtship techniques for different females...even changing from one technique to another if the female doesn't respond to the first. And yes, I've been known to spend a couple of hours watching breeding tubs and have seen a male (Boo exactly) go from heavy on-top non-stop jerky courtship to sly move-along-her-side and just-slip-the-tail over courtship to slow-and-easy half on/half off love-strokes courtship, all on the same female until he finds which one makes her motor run.