Downloaded software to update I photo, run it and still will not work
I am operating OSX 10.8.2.
Details. My iphoto is on an external hard drive. Each time I try to open it I get the message 'To open your library with this version of iPhoto, it first needs to be prepared'. I have downloaded the software and run it but still get error message. I thought the problem may be to do with the fact that the Iphoto is on an external hard drive and the new software is on the Mac so I tried copying my Iphoto back to the computer again. This keeps failing to copy.
Help.
iPhoto '11, OS X Mountain Lion (10.8.2)