When importing Attachments, Attachment fields may contain a path to a file in the Project Home. The path can either be a full directory path like \\servercomputer\CartegraphProjectHomes\ProjectHome\attachments\Signs\mypic.jpg, or use a Directory Variable in the path like <Project Home>\attachments\Signs\mypic.jpg.
In order for these Attachments to display correctly in Cartegraph, the file referenced needs to exist at the location specified in the Attachment field. You may need to move the file to the specified location in the Project Home and make sure that the file name is correct. The import does not move any files referenced in Attachment fields to the Project Home.
If the Attachment is Linked, the field may contain a URL that links to an external file. For example, something like http://www.google.com/mypic.jpg. In order for external linked Attachments to display correctly in Cartegraph, the Attachment field must contain the URL and the Linked field must be set to true.