PY8 "setting mass failed" in neutrino-bottom interaction

Hello all,

Sorry to bother you, but I'm having trouble hadronizing in pythia8 final state quarks produced by neutrino-bottom interactions. For instante, when I try the process:

vm b > vm b

with the following settings:

1 = nevents
0 = lpp1 ! beam 1 type
1 = lpp2 ! beam 2 type
6500.0 = ebeam1 ! beam 1 total energy in GeV
6500.0 = ebeam2 ! beam 2 total energy in GeV
lhapdf = pdlabel ! PDF set
230000 = lhaid ! if pdlabel=lhapdf, this is the lhapdf number
-1.0 = ptl ! minimum pt for the charged leptons

I get the error:

PYTHIA Error in ProcessContainer::constructProcess: setting mass failed
 PYTHIA Abort from Pythia::next: reached end of Les Houches Events File
WARNING in MG5aMC_PY8_interface.cc: Reached end of LHEF after 0 Normalisation will be decreased by-100%.

 *------- PYTHIA Event and Cross Section Statistics -------------------------------------------------------------*
 | |
 | Subprocess Code | Number of events | sigma +- delta |
 | | Tried Selected Accepted | (estimated) (mb) |
 | | | |
 |-----------------------------------------------------------------------------------------------------------------|
 | | | |
 | Les Houches User Process(es) 9999 | 1 1 0 | 0.000e+00 0.000e+00 |
 | ... whereof user classification code 1 | 1 1 0 | |
 | | | |
 | sum | 1 1 0 | 0.000e+00 0.000e+00 |
 | |
 *------- End PYTHIA Event and Cross Section Statistics ----------------------------------------------------------*

 *------- PYTHIA Error and Warning Messages Statistics ----------------------------------------------------------*
 | |
 | times message |
 | |
 | 1 Abort from Pythia::next: reached end of Les Houches Events File |
 | 1 Error in ProcessContainer::constructProcess: setting mass failed |
 | 2 Info from SLHAinterface::initSLHA: No MODSEL found, keeping internal SUSY switched off |
 | 2 Info from SLHAinterface::initSLHA: importing MASS entries |
 | 2 Warning in SLHAinterface::initSLHA: ignoring DECAY tables |
 | 2 Warning in SLHAinterface::initSLHA: ignoring MASS entries |
 | 2 Warning in SLHAinterface::initSLHA: ignoring QNUMBERS |
 | 2 Warning in SLHAinterface::initSLHA: ignoring empty DECAY tables |
 | |
 *------- End PYTHIA Error and Warning Messages Statistics ------------------------------------------------------*

 Contribution of sample 0 to the inclusive cross section : 0.00000000e+00 +- 0.00000000e+00
Inclusive cross section: 0.00000000e+00 +- 0.00000000e+00 mb

I have come to the conclusion that this is related to the neutrino-bottom interaction, because I have tried the processes:

vm u > vm u
vm d > vm d
vm s > vm s

and they work just fine (although vm c > vm c doesn't work either, but for different reasons).

As it was suggested in a previous question, I have also tried:

LesHouches:matchInOut = off

But then I get:

PYTHIA Warning in SimpleSpaceShower::branch: used up beam momentum; retrying parton level
 PYTHIA Error in Pythia::next: partonLevel failed; try again
 PYTHIA Abort from Pythia::next: parton+hadronLevel failed; giving up

 *------- PYTHIA Event and Cross Section Statistics -------------------------------------------------------------*
 | |
 | Subprocess Code | Number of events | sigma +- delta |
 | | Tried Selected Accepted | (estimated) (mb) |
 | | | |
 |-----------------------------------------------------------------------------------------------------------------|
 | | | |
 | Les Houches User Process(es) 9999 | 1 1 0 | 0.000e+00 0.000e+00 |
 | ... whereof user classification code 1 | 1 1 0 | |
 | | | |
 | sum | 1 1 0 | 0.000e+00 0.000e+00 |
 | |
 *------- End PYTHIA Event and Cross Section Statistics ----------------------------------------------------------*

 *------- PYTHIA Error and Warning Messages Statistics ----------------------------------------------------------*
 | |
 | times message |
 | |
 | 1 Abort from Pythia::next: parton+hadronLevel failed; giving up |
 | 10 Error in Pythia::next: partonLevel failed; try again |
 | 2 Info from SLHAinterface::initSLHA: No MODSEL found, keeping internal SUSY switched off |
 | 2 Info from SLHAinterface::initSLHA: importing MASS entries |
 | 2 Warning in SLHAinterface::initSLHA: ignoring DECAY tables |
 | 2 Warning in SLHAinterface::initSLHA: ignoring MASS entries |
 | 2 Warning in SLHAinterface::initSLHA: ignoring QNUMBERS |
 | 2 Warning in SLHAinterface::initSLHA: ignoring empty DECAY tables |
 | 100 Warning in SimpleSpaceShower::branch: used up beam momentum; retrying parton level |
 | |
 *------- End PYTHIA Error and Warning Messages Statistics ------------------------------------------------------*

 Contribution of sample 0 to the inclusive cross section : 0.00000000e+00 +- 0.00000000e+00
Inclusive cross section: 0.00000000e+00 +- 0.00000000e+00 mb

¿What does "setting mass failed mean"? ¿Am I doing something plain wrong?

Cheers,

Saneli