Hi everyone, I am getting following error while running phenix refinement for a protein cocrystalized with a metal chelator complex. What could be the problem. AssertionError : Traceback: File "/Applications/PHENIX-1.7.3-928/Contents/phenix-1.7.3-928/cctbx_project/libtbx/thread_utils.py", line 229, in run return_value = self._target(self._args, self._kwargs, self._c) File "/Applications/PHENIX-1.7.3-928/Contents/phenix-1.7.3-928/cctbx_project/libtbx/runtime_utils.py", line 72, in __call__ result = self.target() File "/Applications/PHENIX-1.7.3-928/Contents/phenix-1.7.3-928/phenix/phenix/refinement/runtime.py", line 67, in __call__ call_back_handler=callback) File "/Applications/PHENIX-1.7.3-928/Contents/phenix-1.7.3-928/phenix/phenix/refinement/command_line.py", line 97, in run call_back_handler=call_back_handler) File "/Applications/PHENIX-1.7.3-928/Contents/phenix-1.7.3-928/phenix/phenix/refinement/driver.py", line 1478, in run ncs_manager = self.ncs_manager) File "/Applications/PHENIX-1.7.3-928/Contents/phenix-1.7.3-928/phenix/phenix/refinement/strategies.py", line 344, in refinement_machine model.show_occupancy_statistics(text = "Occupancies statistics", out=log) File "/Applications/PHENIX-1.7.3-928/Contents/phenix-1.7.3-928/cctbx_project/mmtbx/model.py", line 868, in show_occupancy_statistics self.xray_structure.set_occupancies(value=0., selection = less_than_zero) File "/Applications/PHENIX-1.7.3-928/Contents/phenix-1.7.3-928/cctbx_project/cctbx/xray/structure.py", line 480, in set_occupancies assert selection.size() == s.size() Thanks Subhani