OSX Screen Saver - cant access iphoto library

Hi there, I have been having trouble for some time trying to find out how to get my iphoto library as my screensaver. I have gone through the prefernces options mulitple times to try and find the option to select the library as my source, however I am not given that option when I choose the screen saver settings:

on this page of the apple support:

http://support.apple.com/kb/HT2485

you can see that iphoto library is an option to choose for screen saver images:

I was using the iphoto library in the past, in fact there was a cool mosiac screen saver option that I recall using.

I think I lost the option to choose iphoto library when I upgraded to OS X 10.8

can anyone provide assitance to getting iphoto libaray to once again display as my screen images?

thank you for advice.

-Chris