Hello everybody, I am a new user of Phenix and presently trying to refine 3.6 A data of a protein-RNA complex. whenever i add tls into my .def file for the next run, i get this problem: Traceback (most recent call last): File "/data/software/phenix-1.3b/phenix/phenix/command_line/refine.py", line 5 , in <module> command_line.run(command_name="phenix.refine", args=sys.argv[1:]) File "/data/software/phenix-1.3b/phenix/phenix/refinement/command_line.py", li ne 78, in run call_back_after_monitor_collect=call_back_after_monitor_collect) File "/data/software/phenix-1.3b/phenix/phenix/refinement/driver.py", line 130 8, in run log = log) File "/data/software/phenix-1.3b/phenix/phenix/refinement/strategies.py", line 887, in refinement_machine h_params = h_params) File "/data/software/phenix-1.3b/mmtbx/mmtbx/refinement/adp_refinement.py", li ne 160, in __init__ tools.split_u(fmodel.xray_structure, tls_selections, offset) File "/data/software/phenix-1.3b/mmtbx/mmtbx/tls/tools.py", line 468, in split _u assert (u_iso < 0.0).count(True) == 0 AssertionError I have downloaded the new 1.3b version and without tls the program runs fine! could you please help Thanks in advance Regards kanchan