Cubase 4 osx 10.9.1 file error

Hi I just upgraded to a MacBookPro osx 10.9.1
I installed Cubase AI4 (used on my old macbook os 10.5.8)
installed no problem and works.

However I cannot open my saved project files.
I get the error message “Project “XXXXX” is Cubase Essential Version 4.1.2. Version 4.1.2 Cubase AI Cannot load it”

I also noticed there is a update to C4 4.5.2 available. I tried that as well with no luck.

Any suggestions? Thanks so much!

(I know I need to upgrade to C7)