Hi Edward, I've been trying the new Relax 1.3.7, which has worked well for NOE and R1 calculations, but I'm struggling with the R2. Everything seems to work OK until I get this... ----------------------------------------------------- relax> monte_carlo.setup(number=500) relax> monte_carlo.create_data(method='back_calc') Traceback (most recent call last): File "/home/ms4225/programs/relax-1.3.7/relax-1.3.7/relax", line 348, in <module> Relax() File "/home/ms4225/programs/relax-1.3.7/relax-1.3.7/relax", line 115, in __init__ self.interpreter.run(self.script_file) File "/home/ms4225/programs/relax-1.3.7/relax-1.3.7/prompt/interpreter.py", line 292, in run return run_script(intro=self.__intro_string, local=locals(), script_file=script_file, quit=self.__quit_flag, show_script=self.__show_script, raise_relax_error=self.__raise_relax_error) File "/home/ms4225/programs/relax-1.3.7/relax-1.3.7/prompt/interpreter.py", line 590, in run_script return console.interact(intro, local, script_file, quit, show_script=show_script, raise_relax_error=raise_relax_error) File "/home/ms4225/programs/relax-1.3.7/relax-1.3.7/prompt/interpreter.py", line 476, in interact_script exec_script(script_file, local) File "/home/ms4225/programs/relax-1.3.7/relax-1.3.7/prompt/interpreter.py", line 370, in exec_script runpy.run_module(module, globals) File "/usr/local/lib/python2.6/runpy.py", line 140, in run_module fname, loader, pkg_name) File "/usr/local/lib/python2.6/runpy.py", line 34, in _run_code exec code in run_globals File "/home/ms4225/nmr_data/IGF2R/dynamics/relax/human/curve_fit/600/R2_curve_fit_height/R2_newnew.py", line 118, in <module> monte_carlo.create_data() File "/home/ms4225/programs/relax-1.3.7/relax-1.3.7/prompt/monte_carlo.py", line 77, in create_data monte_carlo.create_data(method=method) File "/home/ms4225/programs/relax-1.3.7/relax-1.3.7/generic_fns/monte_carlo.py", line 70, in create_data data = create_mc_data(data_index) File "/home/ms4225/programs/relax-1.3.7/relax-1.3.7/specific_fns/relax_fit.py", line 501, in create_mc_data value = self._back_calc(spin=spin, relax_time_id=id) File "/home/ms4225/programs/relax-1.3.7/relax-1.3.7/specific_fns/relax_fit.py", line 193, in _back_calc return results[keys.index(relax_time_id)] ValueError: list.index(x): x not in list ------------------------------------------------- Is this a problem with the Analysis2.1/Sparky formatting? I'm not sure because curve fitting seems to work with T1. Madeleine Strickland MCJC Group N317, School of Chemistry, Bristol University