ok, u cannot save if there is already a saved file. Pokemon Diamond (and Pearl) won't let u do that. to erase the already saved file, follow this list of steps: 1) turn on the DS. 2) do whatever you need to do to get to Pokemon Diamond.(If you have your DS set to Manual Mode, touch the screen at credits, then touch Pokemon Diamond; If you have your DS set to Auto Mode, touch the screen at credits; If you have an Action Replay in, touch Start, or set up your cheats then press Start) 3) Press the A button after the dates and stuff, or just let the game show you the whole movie 4) the top screen will say Pokemon Diamond Version Press Start