6 months and not indexed ... suggestions? (google)

It has been over 6 months and one of my sites has yet to be indexed. All of my other sites have been indexed within weeks.

This one that has taken over 6 months has the most content of all of them, and everything is created by me. There are even a few links from some top sites ranked high for my keyword, as well as in some good directories.

I'm really confused here, as I've never had one take this long. Nothing shady is going on, no black hat, etc.

I'm thinking of having it professionally redesigned, adding new content features, etc., but I don't want to go through all that if there's some other problem that is being overlooked.

Any suggestions would be greatly appreciated.

Thanks