You have to add the media assets from the Edit/Team Projects Media Management dialog. It's very different than the normal process.
And it is often best to have the exact folder structure for all media assets duplicated on the local machine, with all media inside the same folders as on the original or "owner" machine/file system. Most dropbox type services cannot provide anywhere near the speed of file transfer needed for working in an editing app like Premiere, with the large video files we so often have.
A partner and I are currently working with the LucidLink service to utilize shared storage and access, and that actually seems to work with online storage. He's in Cape Town, I'm in Oregon, our files are in London ... and we seem to be able to mostly work as though the files were local.
When you say 'empty', is the Team Project panel entirly blank or is the media there but offline?
If it's blank, can you make sure the Team Project owner has already shared the changes with you (Edit > Team Projects > Share My changes...). You in turn would need to get these latest changes once they're shared.
Udo Pawlik | Sr Software Product Quality Specialist | Adobe | firstname.lastname@example.org