Dear bb, I'm using phenix.sort_hetatms to sort my water molecule chain based on their bfactor. My macromolecule and water chains are separated, and I'd very much like them to remain so. When adding *preserve_chain_id=True*, the program outputs: *"Warning: no corresponding macromolecule chain match for C 1"*. The program still writes the output pdb, but it changes the water chain name from "C" to "X", and it does not sort them by bfactor. I'm using Phenix 1.20.1-4487 My command is: *phenix.sort_hetatms file_name="refine.pdb" output_file="resorted_refine.pdb" preserve_chain_id=True sort_waters_by=*b_iso* Not sure where my mistake is. Any suggestions? Best, Victor