# using 'R' in sage: can not plot. errors of X11 and PNG

Hi! We are going to use SAGE this semester in a course which has a piece of statistics. For this part we planned to compile Sage worksheets with the option 'R'. But we have the following errors. If we write the instruction:

**x<-c(12,2,4)**

**y<-x**

**plot(x,y)**

the instruction works in a mac which has a local sage (packages are on the hard disk). However, the pupils will use the sage server of our university (v4.6), wich gives the error message:

**Error in png() : X11 is not available**

The same error is obtained with a local installation on windows 7 (v4.7.2, with VM virtual box).

Besides, if we try at sage server on sagenb.org (v4.7.2), we obtain a different error:

**Error in X11(paste("png::", filename, sep = ""), width, height,
pointsize, :
unable to start device PNG
In addition: Warning message:
In png() : no png support in this version of R**

Please, does anybody know how to fix it?

Thank you.