Derived strain field in triaxial compression test

I am trying to export the Micro-strain legend on the tutorial after performing a triaxial compression test. https://yade-dem.org/doc/user.html#micro-stress-and-micro-strain. But I can't open it with paraview using the generated strain.vtk file. If you can export the changes in the strain field over time with compression, it will be more suitable for me.Thanks for any help.
from yade import pack,plot,qt,export
nRead=readParamsFromTable(
        num_spheres=1000,
        compFricDegree = 50,
        key='_triax_base_',
        unknownOk=True
)
from yade.params import table
num_spheres=table.num_spheres# number of spheres
key=table.key
targetPorosity = 0.42
compFricDegree = table.compFricDegree
finalFricDegree = 50
rate=-0.02
damp=0.2
stabilityThreshold=0.01
young=5e8
mn,mx=Vector3(0,0,0),Vector3(1,2,1) # corners of the initial packing
weiya=400000
poisson=0.1
O.materials.append(FrictMat(young=young,poisson=poisson,frictionAngle=radians(compFricDegree),density=2650,label='spheres'))
O.materials.append(FrictMat(young=young,poisson=poisson,frictionAngle=0,density=0,label='walls'))
walls=aabbWalls([mn,mx],thickness=0,material='walls')
wallIds=O.bodies.append(walls)
psdSizes,psdCumm =[0.19,0.191,0.195,0.196,0.2],[0.,0.1,0.5,0.6,1.]

sp=pack.SpherePack();
sp.makeCloud(mn,mx,num=num_spheres, psdSizes=psdSizes, psdCumm=psdCumm,distributeMass=True,porosity=0.42)
O.bodies.append([sphere(center, rad, material='spheres') for center, rad in sp])
triax=TriaxialStressController(
        maxMultiplier=1.+2e4/young,
        finalMaxMultiplier=1.+2e3/young,
        thickness = 0,
        stressMask = 7,
        internalCompaction=False,
)
newton=NewtonIntegrator(damping=damp)
O.engines=[
        ForceResetter(),
        InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Box_Aabb()]),
        InteractionLoop(
                [Ig2_Sphere_Sphere_ScGeom(),Ig2_Box_Sphere_ScGeom()],
                [Ip2_FrictMat_FrictMat_FrictPhys()],
                [Law2_ScGeom_FrictPhys_CundallStrack()]
        ),
        GlobalStiffnessTimeStepper(active=1,timeStepUpdateInterval=100,timestepSafetyCoefficient=0.8),
        triax,
        TriaxialStateRecorder(iterPeriod=100,file='WallStresses'+table.key),
        newton,
]
yade.qt.Controller(), yade.qt.View()
triax.goal1=triax.goal2=triax.goal3=-weiya
while 1:
  O.run(1000, True)
  unb=unbalancedForce()
  print 'unbalanced force:',unb,' mean stress: ',triax.meanStress
  if unb<stabilityThreshold and abs(-weiya-triax.meanStress)/weiya<0.001:
    break
print "### Isotropic state saved ###"
import sys
while triax.porosity>targetPorosity:
 compFricDegree = 0.95*compFricDegree
 setContactFriction(radians(compFricDegree))
 print "\r Friction: ",compFricDegree," porosity:",triax.porosity,
 sys.stdout.flush()
 O.run(500,1)
print 'Box Volume: ', triax.boxVolume
print "### Compacted state saved ###"
triax.internalCompaction=False
setContactFriction(radians(finalFricDegree))
triax.stressMask = 5
triax.goal1=-weiya
triax.goal2=rate
triax.goal3=-weiya
newton.damping=0.1
O.saveTmp()
TW=TesselationWrapper()
TW.computeVolumes()
TW.volume(20)
TW.setState(0)
O.run(1000,True)
TW.setState(0)
TW.defToVtk("strain.vtk")