Full backward compatibility isn't always possible and it's wise to edit/export the project with the version - or a close version - to the one that created the project.
Old versions are here.
The best way to get help with your work is to share it. This isn't difficult, and someone will be glad to check it out.
Here's how... http://nch.invisionzone.com/topic/23659-tips-for-getting-help-on-this-forum/
If it contains sensitive material you can link it in a personal message (PM) to me, via the envelope above. Be sure to FILE|SAVE PORTABLE PROJECT AS, not simply SAVE PROJECT, and don't forget to share it.
If the project simply won't load, owing to this issue, zip all the source files including the VPJ control file, and upload that folder to the server.