[vlc] problem with mux

[Julião]

I use: *Ubuntu* 11.04
hi, I try to make one video of my desktop and vlc show this error:

$vlc
VLC media player 1.1.9 The Luggage (revision exported)
Blocked: call to unsetenv("DBUS_ACTIVATION_ADDRESS")
Blocked: call to unsetenv("DBUS_ACTIVATION_BUS_TYPE")
[0x23b2120] main libvlc: Running vlc with the default interface. Use 'cvlc'
to use vlc without interface.
Blocked: call to setlocale(6, "")
Warning: call to srand(1305819192)
Warning: call to rand()
Blocked: call to setlocale(6, "")

(process:2488): Gtk-WARNING **: Locale not supported by C library.
 Using the fallback 'C' locale.
Blocked: call to setlocale(6, "")
Warning: call to rand()
Warning: call to rand()
Warning: call to rand()
Warning: call to rand()
[0x7f0a14028ce0] stream_out_standard stream out error: no mux specified or
found by extension
[0x7f0a1403beb0] main stream output error: stream chain failed for
`transcode{vcodec=theo,vb=800,scale=1,acodec=vorb,ab=128,channels=2,samplerate=44100}:file{dst='/home/rsjuliao/Desktop/afafaf'}'
[0x2ccb900] main input error: cannot start stream output instance, aborting

how I can solve this problem?
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