Error in check in packaging: dev.copy2pdf does not work

[vertesy]

Error in check(RepositoryDir, cran = TRUE) in source("~/GitHub/Packages/MarkdownReports/Development/Create_the_MarkdownReports_Package.v4.3.2.R")
I think I had this problem before, but I have no idea how did I resolve it.

> checking examples ... ERROR
  Running examples in ‘MarkdownReports-Ex.R’ failed
  The error most likely occurred in:
  
  > base::assign(".ptime", proc.time(), pos = "CheckExEnv")
  > ### Name: barplot_label
  > ### Title: barplot_label
  > ### Aliases: barplot_label
  > 
  > ### ** Examples
  > 
  > barplot (1:10);
  > barplot_label(barplotted_variable = 1:10, labels = 11:2, filename = "myBarplot.pdf")
  Error in dev.copy2pdf(file = ww.FnP_parser(fname_, "pdf"), width = w_,  : 
    can only print from a screen device
  Calls: barplot_label -> wplot_save_this -> ww.dev.copy -> dev.copy2pdf
  Execution halted