ValueError: cannot convert float to integer

Hi all,

I'm working on my cylinder particle case, however, when I start running my script below, the script points out a ValueError: cannot convert float Nan to integer

** Complete error message **
VaueError Traceback (most recent call last)

/usr/lib/x86_64-linux-gnu/yade/py/yade/__init__.py in refreshValues(self)

                                                              self.iterLabel.setText('#%ld / %ld, %.1f/s %s'% (O.iter,stopAtIter,self.iterPerSec,subStepInfor))
                                                                                              if t!=float('inf'):
                                                                                                          s=int(t); ms=int(t*1000)%1000; us=int(t*1000000)%1000; ns=int(t*1000000000)%1000
                                                                                                          self.virtTimeLabel.setText(u'%03ds%03dm%03d%03dn'%(s,ms,us,ns))
                                                                                              else: self.virtTimeLabel.setText(u'[]?!')
ValueError" cannot convert float NaN to integer

*****: Terminal shows this error multiple times *****

May someone have experience for this error?

### Scripts ###

from __future__ import print_function
from yade.gridpfacet import *
from yade import pack, plot,qt
import gts, os.path, locale

from numpy import arange

O.periodic=True

#### Parameters ####

# radius of cylinder
cyl_R=0.1
# length of cylinder
cyl_L=0.2
# friction angle
phi=30.0
# Young's modulus
E=1e6

idSteel=O.materials.append(FrictMat(young=210e9,poisson=.25,frictionAngle=.8,density=7.85e3,label='steel'))
# wallMask=31 >> +/-x, +/-y, -z
#O.bodies.append(geom.facetBox((0,0,0),(2.5,2.5,1),wallMask=63,material="steel" ))

## create walls
walls=aabbWalls([(0,0,0),(5,5,2)],thickness=0.0,material='steel')
wallIds=O.bodies.append(walls)

### periodic boundary for facetBox ###

#O.cell.setBox(2.5,20.0,20.0)

### set the velocity for facet ###

#for id in range(6):
# b = O.bodies[id]
# b.state.vel = (0,0,0.5)

### create materials ###

# gridConnections material

gridConMat= O.materials.append(CohFrictMat(young=E, poisson=0.5, density=1500, frictionAngle=radians(phi), normalCohesion=1e10, shearCohesion=1e10, momentRotationLaw=True, label='gcMat'))

# general interactions

cylMat= O.materials.append(FrictMat(young=E, poisson=0.5, density=1500, frictionAngle=radians(phi), label='cMat'))

### create particles/packing: cylinders ###

nodesIds=[]
cylIds=[]

dx=0.5
dy=0.5
nx=5
ny=5
nz=1
dz=0

for i in range(0,nx):
 x=0+i*dx
 for j in range(0,ny):
  y=0+j*dy
  for k in range(0,nz):
   z=0+k*dz
   cylinder((x,y+cyl_L,z),(x,y,z),radius=cyl_R,nodesIds=nodesIds,cylIds=cylIds,
color=[1,0,0],fixed=False,intMaterial='gcMat',extMaterial='cMat')

#O.bodies.appendClumped()

move = TranslationEngine(translationAxis=[0,0,1],velocity=0.1,ids=[0,1])

### Engines ###

O.engines = [
 ForceResetter(),
        InsertionSortCollider([Bo1_GridConnection_Aabb(),Bo1_PFacet_Aabb(), Bo1_Wall_Aabb()]),
        InteractionLoop([
   Ig2_GridNode_GridNode_GridNodeGeom6D(),
                  Ig2_GridConnection_GridConnection_GridCoGridCoGeom(),
   Ig2_Wall_Sphere_ScGeom(),
   Ig2_Sphere_Sphere_ScGeom(),
   Ig2_Sphere_GridConnection_ScGridCoGeom(),
   Ig2_GridConnection_PFacet_ScGeom(),
                ],
                [
# internal cylinder physics
           Ip2_CohFrictMat_CohFrictMat_CohFrictPhys(setCohesionNow=True,setCohesionOnNewContacts=False),
# physics for external interactions, i.e., cylinder-cylinder
                        Ip2_FrictMat_FrictMat_FrictPhys()
                ],
                [
                        Law2_ScGeom6D_CohFrictPhys_CohesionMoment(), # contact law for "internal" cylinder forces
                        Law2_GridCoGridCoGeom_FrictPhys_CundallStrack(), # contact law for cylinder-cylinder interaction
   Law2_ScGeom_FrictPhys_CundallStrack(),
   Law2_ScGridCoGeom_FrictPhys_CundallStrack()
   ]
        ),
 GlobalStiffnessTimeStepper(timestepSafetyCoefficient=0.5),
        NewtonIntegrator(gravity=(0., 0., -9.81), damping=0.5, label='newton'),
 move
 #TranslationEngine(translationAxis=[1,0,0],velocity=0.5,ids=[0,1,2,3,4,5])
 #PyRunner(iterPeriod=1e-3,command="")
]

O.dt=0.5*PWaveTimeStep()

#### For viewing ####
qt.View()

#### Allows to reload the simulation ####
O.saveTmp()