When trying to sign a report to be sent automatically via email, I received the following message: The "Signatures for reports" not supported in this edition of Reporting Services. Before any more detailed research I realized I was pointing to a server whose version was SQLServer Express. This version does not have SQLServer Agent, which is who controls the actions of scheduling and execution schedule, among other things, SQLServer. Thus, some attention solve the problem. It was enough to point to the production server, and it opened normally. If you also deal with different versions of SQL Server: stay tuned!
Google translation from original at Portuguese version.