[phenixbb] occupancy refinement question

Hi, I have a ligand with dual conformations. I want to do group occupancy refinement on the conformers (each conformer is one group). I keep having trouble. The ligand is one chain named chain E and conformer 1 has residue name ADRG and conformer 2 has residue name BDRG. This is what I suppose my .def file should have in it: occupancies { individual = None group = "chain E and resname ADRG" group = "chain E and resname BDRG" one_occupancy_group_per_residue = True } When I run this it tells me I have an ambiguous selection. Any ideas why this isn't working and how I can change my .def file to make it work?