It copies the file correctly, it just returns that error, even if I access it directly from the package. 
Running it manually works. 
Adding the step in the win10 installation from scratch works ok. 
  
I fixed the problem by changing the default layout xml directly in the wim, using DISM. 
  
Thank you for your support! 
Best regards! 
  
PS: Looking forward for your guide with the taskbar customization