Why won't google rank my homepage

[DotCar]

I have a site that ranks high on the first page for it's main keyword at both Bing and Yahoo but horribly at Google.  It's a domain I recently acquired and am in the process of optimizing.

My goal is to improve the relevancy for the site in Google so that the site shows up better for it's main keyword.  With that said I've been working on building valuable links to the page and I would like some opinions on why the homepage is not ranking for the main keyword.  Instead I have a junky content page that is ranking for the term.

So in the event that you have a exact match domain showing up very high in Bing and Yahoo but not in Google for the homepage, what factors would you look at?

Add in the complexity that a page other than the homepage is making grounds on the exact match keyword having moved up from "not in the top 100" to the 50's, what's my best solution to ranking the homepage? The site is optimized well and most inbound links predominantly point to the homepage.

[PeterM22]

How old is your site? Sometimes new sites fluctuate all over the place, including the homepage.

[DotCar]

The site is nearly a year old.  The fact that a random page of the site is climbing the ranks for the keyword says to me that Google is not treating the homepage equally.

[EGOL]

Could your homepage be filtered because of duplicate content?

Try some of the sentences from the page in quotes in Google search.

Do you have a million anchor text links from low-quality sites pointing to it with your main keyword?

(This is a tough question to answer from the dark... could be many things... what content was on the homepage before you acquired the domain?)

[DotCar]

The site does not have any duplicate content and does not have overly excessive inbound links.  Anchor tags on the inlinks are reasonable distributed.  As to what took place before acquisitions I don't really know but the entire site is in the index and now I'm working hard to improve relevancy for valuable search queries and to increase conversions.