Diagrams marked with “Powered by VP Online Web Diagram Technologies” are directly edit and stored in the server repository. If you see this message it means the project you working on is not stored/managed by the server repository your VP application now connecting, therefore VP application cannot load the diagram content for you.
If your project is copied from others and he is using Teamwork Server/VP Online as repository then please contact the original project owner invite you to join his repository. After that you can check-out the project from his repository and access to those diagrams. If original project owner is using local embedded server then please ask him export those diagrams from his project for you, so that you can import those diagram to the repository you connecting.