nemo mobile screenshot

[root@localhost ~]# cat screenshot.sh
appenddate=_$(date '+%d%b%y-%H%M%S')
fname=screenshot$appenddate.png
gst-launch-0.10 ximagesrc num-buffers=1 ! ffmpegcolorspace ! pngenc ! filesink location=$fname
[root@localhost ~]# sh screenshot.sh
Setting pipeline to PAUSED ...
ERROR: Pipeline doesn't want to pause.
ERROR: from element /GstPipeline:pipeline0/GstXImageSrc:ximagesrc0: Could not open X display for reading
Additional debug info:
gstximagesrc.c(121): gst_ximage_src_open_display (): /GstPipeline:pipeline0/GstXImageSrc:ximagesrc0:
NULL returned from getting xcontext
Setting pipeline to NULL ...
Freeing pipeline ...
[root@localhost ~]# ls -lh
total 4.0K
-rw-r--r-- 1 root root 165 2013-03-08 13:10 screenshot.sh
-rw-r--r-- 1 root root   0 2013-03-08 13:10 screenshot_08Mar13-131045.png