I upgraded my 2010 MBP to Yosemite and when i try to launch iPhoto it gives me this "The version of iPhoto installed on this Mac is not compatible with OS*X*Yosemite. Download the latest version for free from the Mac App Store" I click on the link in the message and go to iPhoto in the app store and the install button is not clickable. Under purchases it shows iPhoto there as "waiting" but it has been that way for hours. I've updated other apps from the app store just fine after yosemite. Any thoughts? Thanks.