[ESS] ESS Plot from a remote machine

[Riccardo Romoli]

Hi, I get some trouble while I try to use ESS for a remote session via 
tramp. I followed the instruction in the manual section 3.3 but I get 
this error when I try to produce a plot:

========================================
 > plot(1)
Invalid MIT-MAGIC-COOKIE-1 keyError in .External2(C_X11, d$display, 
d$width, d$height, d$pointsize,  :
   unable to start device X11cairo
In addition: Warning message:
In (function (display = "", width, height, pointsize, gamma, bg,  :
   unable to open connection to X11 display ''
 >

========================================

This is my ./ssh/config file:

Host *
Compression yes
CompressionLevel 9
KeepAlive yes

Host erre
      HostName XX.XX.XX.XX
      User erre
      ForwardX11 yes

Host server
      HostName YY.YY.YY.YY
      User service
      ForwardX11 yes


To access the remote machine I have to ssh-jump trought the firewall; 
this is the C-x C-f:

/ssh:service at YY.YY.YY.YY|ssh:erre at XX.XX.XX.XX:/path/to/my/script.R


Where do I wrong? How can I overcome this?

All the best, Riccardo