I do not understand how you are still a permanent resident if you left the U.S. for six years. The law states that there is a conclusive presumption that you abandoned your permanent resident status if you leave the U.S. for over one year.
I recommend that you consult with an experienced immigration attorney before you apply for naturalization. You don't want this application to result in you being placed in removal proceedings.
You may wish to clarify the period you were absent, is it one year or 6 years.
Nonetheless, you are not eligible yet as you have not been present for requisite 5years period.
Contact an immigration lawyer to discuss your case and find a way forward.
The clock for citizenship starts again after a break of one year or longer. Assuming you haven't babandoned your permanent residency you can file 4 years and 9 months after your "break" as long as at least 50% of the time you were physically in the U.S. and have been a resident of the state where you file from for at least 90 days.
Lynne R. Feldman, Attorney at Law
Concentrating in Immigration and Nationality Law
2221 Camino Del Rio South, Suite 201
San Diego, CA 92108
phone: (619) 299-9600, facsimile: (619) 923-3277
Formerly Adjunct Professor -- Immigration law
University of Illinois College of Law
Were you absent continuously for 6 years? If so, as the other response states, you have abandoned your resident status. However, it appears the Service has not deemed that you abandoned your status. Therefore wait until January 2011 & refile.