madspin error (5f scheme ttbar DM): KeyError : ((-5, 5), (-9100022, -6, 6, 9100022))

Dear all,

I am trying to generate dileptonic ttbar events at LO produced in association with DM and no additional jets. In the 4f scheme, everything is working fine, however, when adding b-quarks in the initial state and changing the maxjetflavour option in the run_card, I got the following error from MadSpin:
  KeyError : ((-5, 5), (-9100022, -6, 6, 9100022))
As I am not sure if this is a bug or a problem in my setup, but couldn't find anything in the archive (except inconsistent definitions (p with bb~, but j not) in the 5fscheme causing a similar error message), I would be happy to get some feedback on the issue.
In short I am doing the following:
define p = g u c d s b u~ c~ d~ s~ b~
define vl = ve vm vt
define vl~ = ve~ vm~ vt~
define lept = l+ l- vl vl~
generate p p > t t~ chi chi~ @0

and then for MadSpin
decay t > w+ b, w+ > lept lept
decay t~ > w- b~, w- > lept lept

Please find the MS_Debug output below. I copied the lhe input to this location:
http://www.desy.de/~agrohsje/madspin/

Cheers and thanks for any help, Alexander.

MS_debug:
########

set seed 540687203
import /nfs/dust/cms/user/agrohsje/workarea/cms/gridpacks/madpack_off/genproductions/bin/MadGraph5_aMCatNLO/DMPseudoscalar_ttbar_mphi_100_mchi_1_gSM_1p0_gDM_1p0/DMPseudoscalar_ttbar_mphi_100_mchi_1_gSM_1p0_gDM_1p0_gridpack/work/unweighted_events.lhe.gz
set ms_dir ./madspingrid
set max_running_process 1
decay t > w+ b, w+ > lept lept
decay t~ > w- b~, w- > lept lept
launch
Traceback (most recent call last):
  File "/nfs/dust/cms/user/agrohsje/workarea/cms/gridpacks/madpack_off/genproductions/bin/MadGraph5_aMCatNLO/DMPseudoscalar_ttbar_mphi_100_mchi_1_gSM_1p0_gDM_1p0/DMPseudoscalar_ttbar_mphi_100_mchi_1_gSM_1p0_gDM_1p0_gridpack/work/MG5_aMC_v2_3_3/madgraph/interface/extended_cmd.py", line 908, in onecmd
    return self.onecmd_orig(line, **opt)
  File "/nfs/dust/cms/user/agrohsje/workarea/cms/gridpacks/madpack_off/genproductions/bin/MadGraph5_aMCatNLO/DMPseudoscalar_ttbar_mphi_100_mchi_1_gSM_1p0_gDM_1p0/DMPseudoscalar_ttbar_mphi_100_mchi_1_gSM_1p0_gDM_1p0_gridpack/work/MG5_aMC_v2_3_3/madgraph/interface/extended_cmd.py", line 897, in onecmd_orig
    return func(arg, **opt)
  File "/nfs/dust/cms/user/agrohsje/workarea/cms/gridpacks/madpack_off/genproductions/bin/MadGraph5_aMCatNLO/DMPseudoscalar_ttbar_mphi_100_mchi_1_gSM_1p0_gDM_1p0/DMPseudoscalar_ttbar_mphi_100_mchi_1_gSM_1p0_gDM_1p0_gridpack/work/MG5_aMC_v2_3_3/MadSpin/interface_madspin.py", line 537, in do_launch
    generate_all.run()
  File "/nfs/dust/cms/user/agrohsje/workarea/cms/gridpacks/madpack_off/genproductions/bin/MadGraph5_aMCatNLO/DMPseudoscalar_ttbar_mphi_100_mchi_1_gSM_1p0_gDM_1p0/DMPseudoscalar_ttbar_mphi_100_mchi_1_gSM_1p0_gDM_1p0_gridpack/work/MG5_aMC_v2_3_3/MadSpin/decay.py", line 2100, in run
    self.ending_run()
  File "/nfs/dust/cms/user/agrohsje/workarea/cms/gridpacks/madpack_off/genproductions/bin/MadGraph5_aMCatNLO/DMPseudoscalar_ttbar_mphi_100_mchi_1_gSM_1p0_gDM_1p0/DMPseudoscalar_ttbar_mphi_100_mchi_1_gSM_1p0_gDM_1p0_gridpack/work/MG5_aMC_v2_3_3/MadSpin/decay.py", line 2106, in ending_run
    efficiency = self.decaying_events(self.inverted_decay_mapping)
  File "/nfs/dust/cms/user/agrohsje/workarea/cms/gridpacks/madpack_off/genproductions/bin/MadGraph5_aMCatNLO/DMPseudoscalar_ttbar_mphi_100_mchi_1_gSM_1p0_gDM_1p0/DMPseudoscalar_ttbar_mphi_100_mchi_1_gSM_1p0_gDM_1p0_gridpack/work/MG5_aMC_v2_3_3/MadSpin/decay.py", line 2177, in decaying_events
    production_tag, event_map = self.load_event()
  File "/nfs/dust/cms/user/agrohsje/workarea/cms/gridpacks/madpack_off/genproductions/bin/MadGraph5_aMCatNLO/DMPseudoscalar_ttbar_mphi_100_mchi_1_gSM_1p0_gDM_1p0/DMPseudoscalar_ttbar_mphi_100_mchi_1_gSM_1p0_gDM_1p0_gridpack/work/MG5_aMC_v2_3_3/MadSpin/decay.py", line 3226, in load_event
    P_order = self.all_ME[production_tag]['tag2order'][production_tag]
KeyError: ((-5, 5), (-9100022, -6, 6, 9100022))
Value of current Options:
                 spinmode : madspin
             onlyhelicity : False
                     seed : 540687203
      max_weight_ps_point : 400
                 nb_sigma : 4.5
                 run_card : None
   Nevents_for_max_weigth : 75
                   BW_cut : 15.0
              use_old_dir : False
               max_weight : -1
                 curr_dir : ./madspingrid
                   ms_dir : ./madspingrid
      max_running_process : 1