Ensure you are dragging the turbotax application into the Finder Applications folder directly from the original dmg file you downloaded. You may have inadvertently dragged an alias of the turbotax application into the finder which is why it's still not working. An alias will have a little black "shortcut" style arrow on it. This is not the application. Open the Finder window then the dmg and drag it directly from the dmg over to the Finder. That should resolve it.
