Hello all, I am wondering if anyone has run across this problem and knows how to fix it. I have a twinned dateset and I am using phenix.refine to refine the dataset. I have the full 1.5-2 installation. When I include the twin law (-k, -h, -l) in the refinement, I get this error: File "/usr/swr/phenix-1.5-2/cctbx_project/mmtbx/twinning/twin_f_model.py", line 1651, in map_coefficients "m_gradient" AssertionError If I do not include the twin law, I do not get the error and the refinment continues as normal. When I downgraded to Phenix.1.4-3 (full install), And use the same twin law, I am able to run phenix.refine without an error. I have attached my definition file for phenix.1.5-2 amd the log file. Thanks in advance for any help you can provide, Kelly Daughtry ******************************************************* Kelly Daughtry PhD Candidate Department of Physiology and Biophysics Boston University School of Medicine 590 Commonwealth Ave R 390 Boston MA, 02215 (P) 617-358-5548 *******************************************************