yade.utils.getStressProfile_contact() - did not match C++ signature

Hello All,

I am running this example 'Gravity Deposition' with a slight modification:

# gravity deposition in box, showing how to plot and save history of data,
# and how to control the simulation while it is running by calling
# python functions from within the simulation loop

# import yade modules that we will use below
from yade import pack, plot

# create rectangular box from facets
O.bodies.append(geom.facetBox((.5,.5,.5),(.5,.5,.5),wallMask=63))

# create empty sphere packing
# sphere packing is not equivalent to particles in simulation, it contains only the pure geometry
sp=pack.SpherePack()
# generate randomly spheres with uniform radius distribution
sp.makeCloud((0,0,0),(1,1,1),rMean=.05,rRelFuzz=.5)
# add the sphere pack to the simulation
sp.toSimulation()

O.engines=[
   ForceResetter(),
   InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Facet_Aabb()]),
   InteractionLoop(
      # handle sphere+sphere and facet+sphere collisions
      [Ig2_Sphere_Sphere_ScGeom(),Ig2_Facet_Sphere_ScGeom()],
      [Ip2_FrictMat_FrictMat_FrictPhys()],
      [Law2_ScGeom_FrictPhys_CundallStrack()]
   ),
   NewtonIntegrator(gravity=(-9.81,0,0),damping=0.5),-----------------------------------------(1)
   # call the checkUnbalanced function (defined below) every 2 seconds
   PyRunner(command='checkUnbalanced()',realPeriod=2),
   # call the addPlotData function every 200 steps
   PyRunner(command='addPlotData()',iterPeriod=100)
]
O.dt=.5*PWaveTimeStep()

# enable energy tracking; any simulation parts supporting it
# can create and update arbitrary energy types, which can be
# accessed as O.energy['energyName'] subsequently
O.trackEnergy=True

# if the unbalanced forces goes below .05, the packing
# is considered stabilized, therefore we stop collected
# data history and stop
def checkUnbalanced():
   if unbalancedForce()<.05:
      O.pause()
      plot.saveDataTxt('bbb.txt.bz2')
      # plot.saveGnuplot('bbb') is also possible

# collect history of data which will be plotted
def addPlotData():
   # each item is given a names, by which it can be the unsed in plot.plots
   # the **O.energy converts dictionary-like O.energy to plot.addData arguments
   plot.addData(i=O.iter,CN=utils.getStressProfile_contact(volume=1,ncell=10,dz=1.00,zRef=0.00))----------------------------(2)

# define how to plot data: 'i' (step number) on the x-axis, unbalanced force
# on the left y-axis, all energies on the right y-axis
# (O.energy.keys is function which will be called to get all defined energies)
# None separates left and right y-axis
#plot.plots={'i':('unbalanced',None,O.energy.keys)}
plot.plots={'i':('CN')}
# show the plot on the screen, and update while the simulation runs
plot.plot()

O.saveTmp()

Basically I have just changed the direction of gravity and I am trying to check the static stress profile in the pile.

But doing this throws an error:
ArgumentError: Python argument types in
    yade._utils.getStressProfile_contact()
did not match C++ signature:
    getStressProfile_contact(double volume, int nCell, double dz, double zRef)

Also true with getDepthProfiles/ getStressProfile,etc.
The simulation obviously runs fine without any problem.

I am on the latest YADE version,"Yade 2018.02a-11-dff52bc~xenial".

What exactly is causing this problem?
How to resolve it?
How to get the stress profile otherwise?

Thank you,
Agastya.