H264 over RTSP with GStreamer on 12.1

Hi,
I’m desperately trying to get an RTSP stream containing H264 working with GStreamer under 12.1.
I followed the usual routines, i.e. installing all the gstreamer packages, ffmpeg packges etc. from packman, switched all the packages to packman and what not. I also tried this skript and could not really find any problem.
Manually constructing the GStreamer pipeline results in this:


gst-launch uridecodebin uri=rtsp://192.168.203.218 name=dec dec. ! queue ! ffmpegcolorspace ! xvimagesink dec. ! queue ! audioconvert ! alsasink
Setting pipeline to PAUSED ...
Pipeline is live and does not need PREROLL ...
Setting pipeline to PLAYING ...
New clock: GstSystemClock
Missing element: H264 video RTP depayloader
WARNING: from element /GstPipeline:pipeline0/GstURIDecodeBin:dec: No decoder available for type 'application/x-rtp, media=(string)video, payload=(int)35, clock-rate=(int)90000, encoding-name=(string)H264, packetization-mode=(string)1, profile-level-id=(string)4d0028, sprop-parameter-sets=(string)"Z00AKI2NKA8ARPt4CAQ\=\,aO48gA\=\=", a-recvonly=(string)"", npt-start=(guint64)0, play-speed=(double)1, play-scale=(double)1'.
Additional debug info:
gsturidecodebin.c(874): unknown_type_cb (): /GstPipeline:pipeline0/GstURIDecodeBin:dec
ERROR: from element /GstPipeline:pipeline0/GstURIDecodeBin:dec/GstDecodeBin2:decodebin20: Your GStreamer installation is missing a plug-in.
Additional debug info:
gstdecodebin2.c(3576): gst_decode_bin_expose (): /GstPipeline:pipeline0/GstURIDecodeBin:dec/GstDecodeBin2:decodebin20:
no suitable plugins found
Execution ended after 2237544618 ns.
Setting pipeline to PAUSED ...
Setting pipeline to READY ...
Setting pipeline to NULL ...
Freeing pipeline ...

But upon inspecting the missing element seems to be there after all:


gst-inspect | grep h264
vdpau:  vdpauh264dec: VDPAU H264 Decoder
h264parse:  legacyh264parse: H264Parse
videoparsersbad:  h264parse: H.264 parser
typefindfunctions: video/x-h264: h264, x264, 264
rtp:  rtph264pay: RTP H264 payloader
rtp:  rtph264depay: RTP H264 depayloader
ffmpeg:  ffdec_h264: FFmpeg H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 decoder

What else could I do?