Iphoto two users, instructions not working

My wife and I share a new Macbook. We want to share our iphoto library, and have two users. I have followed apple's instructions (http://support.apple.com/kb/HT1198) and it hasn't work.

I has created a disk images. Changed ownerships, and changed permission. Before and after moving the iphoto file. I've tried starting a new iphoto file in the disk image. I still get permission problems when I fast switch to the other user.

I have restarted and it still doesn't work.

Iphoto will tell me there are permission problem, and then fix them. I switch and there are still problems, and then it fixes them again. I set up photostreams in each, and it will tell me the volume is full (there are 200 gb free)

Any solutions?

I called apple care, and they told me to put the file in a public or shared folder, which does the same thing.

Thanks for your help.

Chris