Re: Double Haul.... Won't.....
From reading your post it sounds like your new rod has a much different action than your previous rod. I expected your newer rod to be a faster action since that seems to be the trend these days but if the new rod flexes all the way to the butt I'm guessing it's a slower action than the old rod. In any case, I would first concentrate on casting the new rod properly. The double haul is simply an enhancement to your cast. Your now using a rod that is a foot longer and with modern (doesn't mean better...) technology. I would concentrate on a basic cast to get your timing adjusted to the new rod. Throw the double haul in later once you have your timing adjusted.
The best way to a fisherman's heart is through his fly.