It seems with geomRootToGeant4 we have many strange warnigns not appearing in the gemRoot case:
-I- Initializing PndSdsDetector()
++++ TG4Warning: ++++
TG4SDServices::GetVolumeID:
Unknown Volume Id for PixelActiveo5oPartAss
+++++++++++++++++++++++
++++ TG4Warning: ++++
TG4SDServices::GetVolumeID:
Unknown Volume Id for PixelActiveo5oPartAss
+++++++++++++++++++++++
++++ TG4Warning: ++++
TG4SDServices::GetVolumeID:
Unknown Volume Id for SciTiloPartAss
+++++++++++++++++++++++
During event loop:
++++ TG4Warning: ++++
TG4MCGeometry::GetTransformation:
Daughter volume &stt01assembly in /cave_1/&stt01assembly_0%stt01tube_57/stt01gas_1 does not exist.
+++++++++++++++++++++++
and
Negative element index in EMC, name=cave
...
maybe detector experts should comment about, I don't have the macros to produce such geometries with TGeoManager (it is more than one detector, as you can see).