newdhfr_un_change.hkl xn_easy_080326a.pdb input.xray_data.labels=FOBSx input.neutron_data.labels=FOBSn xray_data.r_free_flags.generate=True neutron_data.r_free_flags.generate=True refine_default.params

===================== joint neutron/xray refinement start =====================

Traceback (most recent call last):
    call_back_after_monitor_collect=call_back_after_monitor_collect)
File "/usr/local/phenix-1.3-rc4/phenix/phenix/refinement/driver.py", line 1031, in run
    call_back_after_monitor_collect = call_back_after_monitor_collect)
File "/usr/local/phenix-1.3-rc4/phenix/phenix/refinement/strategies.py", line 184, in refinement_machine
    assert not neutron_refinement
AssertionError

I guess in my default parameters, something is wrong, particularly the bold word I highlighted. But I do not know how to fix. Does any one have a clue?\
Thanks and Happy New Year!

main {
    bulk_solvent_and_scale = True
    simulated_annealing = False
    ordered_solvent = False
    ncs = False
    ias = False
    number_of_macro_cycles = 3
    max_number_of_iterations = 25
    use_form_factor_weights = False
    tan_u_iso = False
    use_convergence_test = False
    target = *ml mlhl ml_sad ls
    min_number_of_test_set_reflections_for_max_likelihood_target = 50
    max_number_of_resolution_bins = 30
    reference_xray_structure = None
    use_experimental_phases = None
    compute_optimal_errors = False
    random_seed = 2679941
    scattering_table = wk1995 it1992 *n_gaussian neutron
    use_normalized_geometry_target = True
    target_weights_only = False
    use_f_model_scaled = False
    max_d_min = 0.25
    fake_f_obs = False