Bar Graph Display - only 12 MONTHS!

Hello. I have a report with a bar graph in it and if my selection set brings back more then 12 months worth of data it won't display. It also doesn't just display the first 12 months or the last 12 months. It displays months from all over.

Example:

Return 2-1-04 to 2-1-06

Displays: Feb04, Jun04, July04, May05, Jun05, July05, Aug05, Sept05, Oct05, Nov05, Dec05, Jan06

There is data available for every month within that range. Is there a setting that I am missing What can I do

Please Help!

Thanks in Advance!

Jen