problems of multiscale coupling of DEM-FEM

Hi：
I run the multiscale example of demfemcoupling by Jan Stranský and find that the x and y displacements of points are 0? The boundary conditions of point in the example are f(x)=0,f(y)=0,f(z)=F(t).
Here is the code of bcs:
# boundary condition and time function
ltf = liboofem.loadTimeFunction("pieceWiseLinFunction",1,nSteps=2,t=(0,2e-1),f_t=(0,1))
bcs = [liboofem.boundaryCondition(i+1, domain, loadTimeFunction=1, prescribedValue=v) for i,v in enumerate((0,-1.0))]
Yours,
Joe