Dear Phenixers, I have a low resolution twinned data, for which I disabled cross validation in refinement. The refinement worked and exported the refined coordinates. However, the phs files for maps are empty and there were such errors as below. It seems the free set is required for maps. I wonder how to fix this problem? Thanks Chen Traceback (most recent call last): File "/home/chene/phenix-1.6.4-486/phenix/phenix/command_line/refine.py", line 11, in <module> command_line.run(command_name="phenix.refine", args=sys.argv[1:]) File "/home/chene/phenix-1.6.4-486/phenix/phenix/refinement/command_line.py", line 103, in run map_manger.write_files() File "/home/chene/phenix-1.6.4-486/phenix/phenix/refinement/driver.py", line 1281, in write_files fmodel = self.refine_object.fmodels.fmodel_xray(), params = mtz_mc) File "/home/chene/phenix-1.6.4-486/cctbx_project/mmtbx/maps/__init__.py", line 290, in map_coefficients_from_fmodel centrics_pre_scale = params.centrics_pre_scale) File "/home/chene/phenix-1.6.4-486/cctbx_project/mmtbx/twinning/twin_f_model.py", line 1780, in map_coefficients w2 = w2) File "/home/chene/phenix-1.6.4-486/cctbx_project/mmtbx/twinning/twin_f_model.py", line 1695, in map_coefficients sigmaa_object = self.sigmaa_object( detwinned_data=dt_f_obs,f_model_data=tmp_f_model, tmp_free=tmp_free,forced_update=True) File "/home/chene/phenix-1.6.4-486/cctbx_project/mmtbx/twinning/twin_f_model.py", line 1504, in sigmaa_object kernel_width_free_reflections=200, File "/home/chene/phenix-1.6.4-486/cctbx_project/mmtbx/scaling/sigmaa_estimation.py", line 131, in __init__ raise RuntimeError("No free reflections.") RuntimeError: No free reflections. Chen Chen, PhD, Research Associate Center for Advanced Research in Biotechnology (CARB), University of Maryland Biotechnology Institute (UMBI), 9600 Gudelsky Drive, Rockville, MD 20850 240-314-6122