why gst-launch doesnot work in my Ubuntu?

[Tom]

I run:
gst-launch filesrc "location=1.MPG" ! decodebin ! video/x-raw-yuv,
width=640,height=480,framerate=5/1 ! ffmpegcolorspace ! jpegenc !
multipartmux ! tcpserversink host=192.168.2.1 port=5000

and then got an error:
(gst-launch-0.10:10770): GLib-WARNING **: g_set_prgname() called multiple
times
Setting pipeline to PAUSED ...
Pipeline is PREROLLING ...
ERROR: from element
/GstPipeline:pipeline0/GstDecodeBin:decodebin0/GstMpegPSDemux:mpegpsdemux0:
Internal data stream error.
Additional debug info:
gstmpegdemux.c(2734): gst_flups_demux_loop ():
/GstPipeline:pipeline0/GstDecodeBin:decodebin0/GstMpegPSDemux:mpegpsdemux0:
stream stopped, reason not-negotiated
ERROR: pipeline doesn't want to preroll.
Setting pipeline to NULL ...
Freeing pipeline ...

I don't know why.....

I have sent an email in email list about my question. I post it here again
for you convenience:
I want to stream a video on a Linux PC. This means there is a (mpeg) video
file on this Linux PC, and This LINUX PC is a streaming server.
Another LINUX PC is used to receive the video stream by some media player
such as VLC player.
The properties of this video streaming, such as the rate of I-frame,
B-frame, P-frame, etc, are possible to be revised when i run the command in
the future.

So could you please reply me a specific command line? (I did read the
website replied in this email list, but got confused sometime)
Thanks!

Tom
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