Iphoto not saving changes

I have recently been spending a great deal of time playing with Iphoto such as adding keywords, rating photos, making titles, manipulating photos. Unfortunately, after hours of playing, I find out the next time I open the application, that changes were not saved. I am trying to give each photo metadata to be able to sort later. What gives? Does having my library on an external drive have anything to do with this? Has this happened to anyone else?

Is it possible that you have your images in two Libraries? I'm thinking that you may be editing one, then accessing the other and wondering why your edits were not saved.

Maybe. However, since I changed my library to an external drive, every time I open iphoto it should be accessing this directory. I'll check on it.