uck does not seem to work due to remaster-iso/casper/filesystem.squashfs: failed to setup loop device: No such file or directory

[Muelli]

I've tried to use uck but with no success:

(zenity:17110): Gtk-WARNING **: gtk_widget_size_allocate(): attempt to allocate widget with width 13 and height -5
Gtk-Message: GtkDialog mapped without a transient parent. This is discouraged.
Gtk-Message: GtkDialog mapped without a transient parent. This is discouraged.
Gtk-Message: GtkDialog mapped without a transient parent. This is discouraged.
Preparing build environment...
Creating X authentication cookie...
Running build process...
Build (/usr/bin/uck-gui ) started at 2016-05-23 18:41:32
>> Ubuntu Customization Kit 2.4.7 on Ubuntu 16.04, 4.6.0-040600-generic x86_64
Starting CD remastering on Mo 23. Mai 18:41:32 CEST 2016
Customization dir=/home/muelli/tmp/customization-scripts
Mounting ISO image...
mount: /dev/loop0 is write-protected, mounting read-only
Unpacking ISO image...
Unmounting ISO image...
Mounting SquashFS image...
mount: /home/muelli/tmp/remaster-iso/casper/filesystem.squashfs: failed to setup loop device: No such file or directory
Cannot mount /home/muelli/tmp/remaster-iso/casper/filesystem.squashfs in /home/muelli/tmp/remaster-root-mount, error=32
Gtk-Message: GtkDialog mapped without a transient parent. This is discouraged.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: uck 2.4.7-0ubuntu2
Uname: Linux 4.6.0-040600-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CurrentDesktop: GNOME
Date: Mon May 23 18:42:28 2016
InstallationDate: Installed on 2015-12-02 (173 days ago)
InstallationMedia: Ubuntu-GNOME 16.04 LTS "Xenial Xerus" - Alpha amd64 (20151027)
PackageArchitecture: all
SourcePackage: uck
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.