Dear Phenix users, here you have an error occurred during a DEN refinement cycle on a twinned structure. Please, help me in order to overcome the problem. This is the command line I used to run phenix: phenix.den_refine data.mtz model.pdb twin_law=h,-k,-l output.prefix=DEN10 --overwrite main.ncs=true set_b_iso=50 convert_to_isotropic=true xray_data.high_resolution=3.6 nproc=4 secondary_structure_restraints=true optimize_xyz_weight=true optimize_adp_weight=true reference_model.file=3ZVJ-coot1.pdb use_geometry_restraints=true den.params fix_rotamers=true den.params is attached I was running phenix dev-1145 on a 64bit Debian machine. This is the error message: Running DEN torsion optimization on 4 processors... Running torsion simulated annealing ...trying gamma 0.0, weight 100.0 ...trying gamma 0.2, weight 100.0 ...trying gamma 0.0, weight 300.0 ...trying gamma 0.2, weight 300.0 Traceback (most recent call last): File "/usr/local/phenix-dev-1145/build/intel-linux-2.6-x86_64/../../phenix/phenix/command_line/den_refine.py", line 21, in <module> den_refine.run(command_name="phenix.den_refine", args=sys.argv[1:]) File "/usr/local/phenix-dev-1145/phenix/phenix/refinement/den_refine.py", line 113, in run customized_master_params=master_phil) File "/usr/local/phenix-dev-1145/phenix/phenix/refinement/command_line.py", line 146, in run call_back_handler=call_back_handler) File "/usr/local/phenix-dev-1145/phenix/phenix/refinement/driver.py", line 1532, in run ncs_manager = self.ncs_manager) File "/usr/local/phenix-dev-1145/phenix/phenix/refinement/strategies.py", line 830, in refinement_machine log=log) File "/usr/local/phenix-dev-1145/cctbx_project/mmtbx/den/refinement.py", line 88, in __init__ "serious error; please contact [email protected].") % so) RuntimeError: DEN weight optimization failed: DEN cycle 1 rfree at start of SA cycle: 0.4642 k_rep = 1.00 tardy_tree summary: number of vertices: 16570 number of edges: 16855 find cluster loops: 0 repeats number of fixed vertex lists: 0 number of fixed vertices: 0 number of clusters: 7857 merge clusters with multiple connections: 1 pass number of hinge edges: 7857 number of loop edges: 0 number of loop edge bendings: 0 number of fixed hinges: 0 CAUGHT EXCEPTION: (argument #0) ARGUMENT LEADING TO EXCEPTION: (0.0, 100.0) Traceback (most recent call last): File "/usr/local/phenix-dev-1145/cctbx_project/libtbx/easy_mp.py", line 155, in __call__ result = O.func(arg) File "/usr/local/phenix-dev-1145/cctbx_project/mmtbx/den/refinement.py", line 227, in try_den_weight_torsion call_back_after_step=False) File "/usr/local/phenix-dev-1145/cctbx_project/mmtbx/refinement/tardy.py", line 228, in run reduced_geo_manager=reduced_geo_manager) File "/usr/local/phenix-dev-1145/cctbx_project/mmtbx/refinement/tardy.py", line 86, in __init__ O.weights = target_weights.xyz_weights_result AttributeError: 'NoneType' object has no attribute 'xyz_weights_result' This is a serious error; please contact [email protected]. Thanks in advance Fulvio Saccoccia PhD student Dept. of Biochemical Sciences Sapienza University of Rome +390649910556