Because you're running a version of iPhoto that is 2 versions old and was superseded back in January, 2009. Everyone has to purchase upgrades from one version to another every since iLife 04. Updates within a version, i.e. 8.1 to 8.1.2 are free.
The History of iLife
Version | Intro | Cost | OS | IPhoto | iWeb | iMovie | iDVD | iTunes | Gband |
---|
iLife | 01/03/03 | $49 | 10.1 | 2 | – | 3 | 3 | 3 | – |
iLife 04 | 01/06/04 | $49 | 10.2.6 | 4 | – | 4 | 4 | 4.2 | 1 |
iLife 05 | 01/11/05 | $49 | 10.3.4 | 5 | – | HD 5 | 5 | 4.71 | 2 |
iLife 06 | 01/10/06 | $79 | 10.4.3 | 6 | 1 | HD 6 | 6 | 6.0.2 | 3 |
iLife 08 | 08/07/07 | $79 | 10.4.9 | 7.0 | 2.0 | 7.0 | 7.0 | – | 4.0 |
iLife 09 | 01/06/09 | $79 | 10.5.6 | 8.0 | 3.0 | 8.0 | 7.0.3 | – | 5.0 |
iLife 11 | 10/20/10 | $49 | 10.6.3 | 9.0 | 3.02 | 9.0 | 7.1 | – | 6.0 |
If you want to go the long route you can purchase the iLIfe 11 disc from a 3rd party retailer like Amazon.com: iLife 11 to get iPhoto 9 and then go thru the many updaters available from the Apple Downloads webpage to get to the current 9.4.1. This way you'll also get a copy of iDVD and iWeb which have been discontinued if you don't already have them.
OT