FAQ > Why the Scan button is disabled? / Why my catalog is not writable?
(1) When another user / app / Mac is using your catalog file, DiskCatalogMaker will open it with the read-only mode. Please close another app.
(2) If the current login user does not have the write permissions of the catalog file, DiskCatalogMaker will open it with the read-only mode.
You can change the permissions at the Get Info window of Finder.
FAQ> Where is my catalog file?
You can also make a writable copy of your catalog file using "Save As..." in the File menu of DiskCatalogMaker.