Problems Matching/Merging @ NLO for top quark partner

Dear Experts,

I am having a bit of trouble matching and merging @ NLO of a fermionic top quark partner with up to one jet (at born level), and hope some light can be shed on the issue.

The model is a SM + massive fermionic top quark partner (t2) with SU(3)xSU(2)xU(1) quantum numbers of (3,1,+2/3). QCD renormalization and R2 terms were generated with FeynRules/NLOCT, etc. Making the appropriate parameter choices, the following processes
p p > a > t2 t2~ QED=2 QCD=0
p p > t2 t2~ QCD=2 QED=0
p p > t2 t2~ QCD=2 QED=0 [QCD]
were found to match the SM analogue. The bottom quark mass was kept.

Next, I did the following:
import ....
define p = g u c d s u~ c~ d~ s~
define j = g u c d s u~ c~ d~ s~
generate p p > t2 t2~ QED=0 [QCD] @0
add process p p > t2 t2~ j QED=0 [QCD] @1
output ....

As a check, the FxFx merging instructions were executed successfully for top quark pair production using the same model. Using the same setup but for the top quark partner I received the following output:

launch -f
INFO: Enter mode value: Go to the related mode
INFO: will run in mode: aMC@NLO
WARNING: You are running with FxFx merging enabled. To be able to merge
    samples of various multiplicities without double counting, you
    have to remove some events after showering 'by hand'. Please
    read http://amcatnlo.cern.ch/FxFx_merging.htm for more details.
INFO: Starting run
INFO: Compiling the code
INFO: For gauge cancellation, the width of 'T2' has been set to zero.
INFO: Using built-in libraries for PDFs
INFO: Compiling source...
INFO: ...done, continuing with P* directories
INFO: Compiling directories...
INFO: Compiling on 4 cores
...
...
INFO: Starting run
INFO: Using 4 cores
INFO: Cleaning previous results
INFO: Doing NLO matched to parton shower
INFO: Setting up grid
WARNING: program .../SubProcesses/P1_gu_t2t2xu/ajob2 2 F 0 launch ends with non zero status: 1.
Stop all computation
INFO: Idle: 46, Running: 0, Completed: 4 [ current time: 15h08 ]

At this point, the program just hangs. The output of the associated log file is the following:

launch -f
Traceback (most recent call last):
  File ".../bin/internal/extended_cmd.py", line 889, in onecmd
    return self.onecmd_orig(line, **opt)
  File ".../bin/internal/extended_cmd.py", line 882, in onecmd_orig
    return func(arg, **opt)
  File ".../bin/internal/amcatnlo_run_interface.py", line 1203, in do_launch
    evt_file = self.run(mode, options)
  File ".../bin/internal/amcatnlo_run_interface.py", line 1565, in run
    self.run_all(job_dict, [['2', 'F', '%d' % i]], status, split_jobs = split)
  File ".../bin/internal/amcatnlo_run_interface.py", line 3308, in run_all
    self.wait_for_complete(run_type)
  File ".../bin/internal/amcatnlo_run_interface.py", line 3272, in wait_for_complete
    self.cluster.wait(self.me_dir, update_status)
  File ".../bin/internal/cluster.py", line 815, in wait
    raise Exception, self.fail_msg
Exception: program .../SubProcesses/P1_gu_t2t2xu/ajob2 2 F 0 launch ends with non zero status: 1. Stop all computation

Any thoughts and suggestions would be very much appreciated. Thank you.

Best Wishes,
Richard Ruiz