Apple changed some things at a certain point in time where the charging pin in the connector changed (I believe - a little fuzzy on the details). Esentially, you could buy a new cord (as menioned above) or a converter. I bought a Scosche Passport from the Apple store, and it solved my problem.
http://store.apple.com/us/product/TS696LL/A
I had to really push the people at the apple store and tell them exactly what I needed. Frankly, I would just order it online.
The new cord may be a more elegant solution, however, I would talk with someone who is using it in their infiniti before purchasing. That brandmotion seems to be for Fords.
The adaptor works well, but is a bit awkward to and makes it bulkier and harder to fit the phone/cord/adaptor into the center bin.