Red Dead Redemption Duel with Harold in Black Water?

So Ive seen the answers about dueling in red dead redemption. My bar is higher than the other guy but he still beats me. This guy in Particular. Harold in Black water. Even if i do it faster than him he still beats with me a lower level bar. I guess i don't truly understand how to duel yet.There has to be a pattern with the bars on the lower right corner?? Someone help?