Hello everyone  

I want to create a lead for a 3D structure, but when I run the program,
I get the following error: 

###No sites close to (0, 0, 14) are inside the desired shape.### 

Please help me find the mistake. 

Thanks in advance for your reply. 

#### 

import kwant
from matplotlib import pyplot 

lat = kwant.lattice.general([(0, 0.5, 0.5), (0.5, 0, 0.5), (0.5, 0.5,
0)],
[(0, 0, 0), (0.25, 0.25, 0.25)], name=['a1', 'a2'])
a1, a2 = lat.sublattices 

def make_cuboid(a=10, b=10, c=15):
def cuboid_shape(pos):
x, y, z = pos
return 0 <= x < a and 0 <= y < b and 0 <= z < c

syst = kwant.Builder()
syst[a1.shape(cuboid_shape, (0, 0, 0))] = 1 ## the same on-site foar a1
and b1
syst[a2.shape(cuboid_shape, (0, 0, 0))] = 1
syst[lat.neighbors()] = 1

def lead_shape(pos):
x,y,z = pos
return 0 <= x < a and 0 <= y < b and 14 <= z < c

lead = kwant.Builder(kwant.TranslationalSymmetry([1,0,0]))
lead[lat.shape(lead_shape, (0, 0, 14))] = 1
lead[lat.neighbors()] = 1

return syst,lead 

def main():

syst,lead = make_cuboid() 

kwant.plot(syst)

syst = syst.finalized()

syst = make_cuboid(a=1.1, b=1.1, c=1.1)

def family_colors(site):
return 'r' if site.family == a1 else 'g' 

syst.attach_lead(lead)

kwant.plot(syst, site_size=0.18, site_lw=0.01, hop_lw=0.05,
site_color=family_colors)

if __name__ == '__main__':
main() 

#####

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