Hi,
All versions of PD are backward compatible, .pds files created in earlier versions will be able to be processed by later versions. However, wether the actual project can be fully opened will depend on all the assets used in the original project being still available with the same file names and path locations.
If they are not, then the.pds file cannot automatically find them, you should be asked to find them manually, and point PD to them. If you cannot find them the timeline will have blank spaces where the missing files should be.
It gets complicated, but there are ways to find out the file names and locations, if necessary.
You need to give members more information on what is actually happening when you try to open the earlier project.
Cheers
PowerDirector Moderator