hybrid sph granular simulation

Hi all,

I am trying to run a simulation with a hybrid granular and sph model. My first attempt was using the sph example case (liggghts 1.5.0) and replacing
atom_style sph
by
atom_style hybrid sph granular
I ended up with the appended input file. I'd expect that the system behaves exactly like the sph example but
* instead of creating a wave that moves smoothly back and forth the particles just fall in -z direction
* also I get an error: ERROR on proc 0: Particle on or inside fix wall/region/sph surface

Did I make a mistake? Is SPH incompatible with the hybrid atom style?

Thanks for any comments!
Cheers,
Moritz