Nugget value is always zero while using scikit-geostat

Question

import numpy as np
import skgstat as skg

coordinates = long_data
values =N_data

V = skg.Variogram(coordinates=coordinates, values=values ,maxlag=np.max(dists)/2.0 , use_nugget =True )
print(V)
V.plot()

enter image description here

from the graph it is clear that nugget value is not zero but it gives value as 0

Output:

-------------------
Estimator:         matheron
Effective Range:   2.89
Sill:              0.00
Nugget:            0.00