problem with 12/16 beaming

[Stefan Thomas]

Hi together,
I have a problem with auto beams in the 12/16 bar.
I want beam the 16th in groups of three notes, but it doesn't work in
the below quoted file:

\relative c
{
\clef bass
\time 12/16
 #(override-auto-beam-setting '(end * * 12 16) 3 16 'Score)
c16 b c d c d g, a b c d e
}

What's the mistake?
Thanks for Your support.
Stefan