This occurs when running phenix.refine_gui with twin mode turned on.
 
A Python error was detected.  This is almost certainly a bug; please send an email containing this message to [email protected] so we can fix it.  Thanks!
 
TypeError : float argument required, not NoneType
Traceback:
Traceback (most recent call last):
  File "/protos/package/strucbio/phenix-1.4-3/phenix/wxGUI2/Refine.py", line 269, in OnUpdate
    self.notebook.run_tab.OnStatsUpdate(event)
  File "/protos/package/strucbio/phenix-1.4-3/phenix/wxGUI2/RefineNotebook.py", line 277, in OnStatsUpdate
    self.xyzerr_val.SetLabel("%.2f" % f_info.ml_coordinate_error)
TypeError: float argument required, not NoneType
 
Mark Knapp
Structural Chemistry
NIBR
4560 Horton Street M/S 4.4
Emeryville, CA 94608
510-923-6926