Tvheadend

I'm trying to stream the camera of an raspberry pi on tvheadend as IPTV. As mux URL I have something like pipe:///path/script.sh. The main command of this script is:
ffmpeg -loglevel fatal -i udp://@:7777 -vcodec copy -acodec none -metadata service_provider=$PROVIDER -metadata service_name=$SERVICE -f mpegts pipe:1

The format looks correct:

Input #0, mpegts, from 'udp://@:6001':
  Duration: N/A, start: 2047.560000, bitrate: N/A
  Program 1 
    Stream #0:0[0x100]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p, 1920x1080, 25 fps, 25 tbr, 90k tbn, 180k tbc
Output #0, mpegts, to 'pipe:1':
  Metadata:
    service_provider: surveillance
    service_name    : kitchen
    encoder         : Lavf56.25.101
    Stream #0:0: Video: h264 ([27][0][0][0] / 0x001B), yuv420p, 1920x1080, q=2-31, 25 fps, 25 tbr, 90k tbn, 90k tbc
Stream mapping:
  Stream #0:0 -> #0:0 (copy)

Querying the mux, the service 'kitchen' appears in the specific tab but if I try to query the service (using something like 'curl http://host:9981/play/stream/service/...') nothing is given and tvheadend says 'service instance is bad, reason: No input detected'. It looks like tvheadend expect something different than a mpegts stream. How can I map the video stream on a channel if the created service goes on error?

Thanks you!