/dev/null: Permission denied.

I am never able to use the tool without it failing, and it always seems to stem from this error: "/tmp/customization-scripts/customize: line 69: /dev/null: Permission denied"
All I do is run uck-gui, pick french and english options on the language windows, set english as default, then I tell it to use the gnome desktop, then I pick my CD image (Ubuntu 12.10 Desktop 64-bit), say yes to customize it manually, yes to delete Windows-related files, and yes to hybrid image. I let it get to work. I notice some warnings about ~/tmp/remaster-iso-mount being mounted read-only, and also remaster-root-mount. It is during the updating process that comes next that I begin seeing errors about not being able to create and access /dev/null. The initial error is this: "sh: 1: cannot create /dev/null: Permission denied" and all afterwords are like the one I described in the first sentance. It used to ask me if I would like to customize or continue build process, and I would click customize, but then the same window would pop back up until I instead chose Continue build process, at which point it would fail. it no longer eve asks me that anymore.