Javier --
You left out one very important piece of information in your post: Have you
changed the default Group/Category permissions in Project Server? By
default, members of the Project Managers can can only see, open, and edit
their own projects. Assuming you have not changed the default permissions
in Groups and Categories, you would need to do the following:
1. Create a custom Category that includes only this one project.
2. Create a custom Group and add the people who need to be able to see,
open, and edit the project.
3. In the custom Group, add the custom Category.
4. In the Permissions grid for the custom Category, select the Project and
Resource permissions for this Group.
5. In the Global Permissions grid, set the permissions for this Group.
Hope this helps.