This message has the following cause and solution:
The share of the database name file (.acn file) has taken place in your source code control system, but not in Microsoft Access. In general, every project should already contain a database name file, and no project should ever have more than one. Therefore, sharing one into a project is not recommended.
To avoid having an invalid database, run Visual SourceSafe and use the Delete command to remove the newly shared .acn file.