Time Machine won't display back ups past 1 year? iphoto album needed.

I'm running 10.8.4 on my iMac with iPhoto 11. I have an external drive with Time Machine backups going back to 2009. I need to open an iphoto library from 2011 but when I open Time Machine on my iMac with the drive connected the purple slider on the right only shows me windows back to May 2012. I tried opening iPhoto with option button held down and selecting the 2011 library from the folder via Finder but it's dimmed out and I can't select it. I tried just grabbing it and copying it to my desktop. If I double click on it I can open iphoto and see the library and see all the names of the folders and even the number of photos in each folder but each photo is just a blank box. When I click on the photo a triangle with a ! comes up inside the box. Help!