Office Binder document type (.doc) not c

IAW Office Binder Help instructions, I opened Windows Explorer and Office Binder; each time I try to drag .doc files to the Binder, I receive the following error: The document filename.doc cannot be added to the binder because the document type is not compatible with Office Binders. Initial use successful; subsequent uses unsuccessful. What could cause this document type not compatible message to appear? I tried Section and File but received the same error. Looking for troubleshooting documentation & advice with solution(s).