formatR tidy_souce() does not work for clipboard

Question

I have tried the tidy_source() on my windows machine and it worked just fine. However it fails when I try to run tidy_source() on a Ubuntu machine.

> sessionInfo()
R version 3.2.1 (2015-06-18)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 14.04.2 LTS

locale:
 [1] LC_CTYPE=en_SG.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=en_SG.UTF-8        LC_COLLATE=en_SG.UTF-8    
 [5] LC_MONETARY=en_SG.UTF-8    LC_MESSAGES=en_SG.UTF-8   
 [7] LC_PAPER=en_SG.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_SG.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] formatR_1.2

loaded via a namespace (and not attached):
[1] tools_3.2.1  grid_3.2.1   stats4_3.2.1

The sample text to be formatted is copied into clipboard, and then I ran tidy_source(). Error message shows up, where the arrow is pointing to an invalid character (not displayed in R):

> tidy_source()
Error in parse(text = x, keep.source = TRUE) : 
  <text>:1:1: unexpected input
1: 
    ^

The same procedure works for R on a Windows machine, and (apparently) on a linux machine in the example provided in the formatR package.

The following sample code works fine:

## a messy R script
messy = system.file("format", "messy.R", package = "formatR")
tidy_source(messy)

Am I doing something wrong here? Or am I missing something important?

EDIT: following comment suggestions, I have tried the following variations when calling the function, but none of them seems to work.

> tidy_source(source = "X11_clipboard")
Error in file(con, "r") : 
  X11 clipboard selection is not supported on this system
> tidy_source(source = "X11_primary")
Error in parse(text = x, keep.source = TRUE) : 
  <text>:1:1: unexpected input
1: 
    ^
> tidy_source(source = "X11_secondary")
Error in file(con, "r") : cannot open the connection
In addition: Warning message:
In file(con, "r") : clipboard cannot be opened or contains no text