Visual SourceSafe must map the local copy into a Visual SourceSafe project path for this operation to work. This error has the following cause and solution:
You added a file from a folder other than your project folder (or one of its subdirectories), and Visual SourceSafe cannot determine which Visual SourceSafe project corresponds to your new file's home folder.
Click Yes if you want to copy the file to the folder named. Copy the file to a subfolder at or below your project. If the file is already in Visual SourceSafe in a different project, share the file to your current project, and try the operation again.
Click No if you do not want to continue this operation. You can later copy or share the file and try the request again.