Building failed

i have this issue, when the software try to copy the next file:

Build (/usr/bin/uck-gui --wait-before-exit) started at 2019-02-13 23:43:39
>> Ubuntu Customization Kit 2.4.7 on Ubuntu 18.04, 4.15.0-45-generic x86_64
Starting CD remastering on mié feb 13 23:43:43 -05 2019
Customization dir=/home/logiqtest/tmp/customization-scripts
Mounting ISO image...
mount: /home/logiqtest/tmp/remaster-iso-mount: WARNING: device write-protected, mounted read-only.
Unpacking ISO image...
Unmounting ISO image...
Mounting SquashFS image...
Unpacking SquashFS image...
Unmounting SquashFS image...
Creating apt cache...
Creating root home...
Mounting /proc
Mounting /sys
Mounting /dev/pts
Mounting /tmp
Mounting /home/logiqtest/tmp/remaster-root-home
Mounting /home/logiqtest/tmp/remaster-apt-cache
Mounting /run
Mounting /home/logiqtest/tmp/customization-scripts
Copying fstab/mtab...
cp: '/etc/mtab' and '/home/logiqtest/tmp/remaster-root/etc/mtab' are the same file
Unmounting /home/logiqtest/tmp/remaster-root/var/cache/apt...
Unmounting /home/logiqtest/tmp/remaster-root/tmp/customization-scripts...
Unmounting /home/logiqtest/tmp/remaster-root/tmp...
Unmounting /home/logiqtest/tmp/remaster-root/sys...
Unmounting /home/logiqtest/tmp/remaster-root/run...
Unmounting /home/logiqtest/tmp/remaster-root/root...
Unmounting /home/logiqtest/tmp/remaster-root/proc...
Unmounting /home/logiqtest/tmp/remaster-root/dev/pts...
Failed to copy mtab, error=1
Gtk-Message: 23:46:09.676: GtkDialog mapped without a transient parent. This is discouraged.

I appreciate the help