Hi,
I had a similar problem where our homepage was out ranking the target page. It was down to a number of things but mainly the fact that a lot of links using the keyword anchor text were pointed at the homepage. I would be surprised if your new page replaces the homepage in the SERPs soon after launching it. You'll need to do a few things first.
- Either build new links or get the existing links repointed to your new landing page
- Make sure your on-page SEO is spot on
- Use your internal links effectively to point to your new page using the targeted keyword
Hope that helps,
Brendan.