Movian

I'm making some first steps with Showtime on Raspberry and try to enable the composite video output. Everything else including HDMI output works.

I tried the common way of adding the following parameters to config.txt file:
sdtv_mode=2
sdtv_aspect=1

When I remove HDMI cable and use composite video during boot I only have a black screen after the typical boot messages.

Is there something else I can try or is composite output simply not supported by Showtime at the moment?

Many thanks!