  By studying an explicit analytical solution of the Coulomb problem on the
lattice we demonstrate a breakdown of perturbative matching for the description
of the Coulomb artifacts in lattice NRQCD, which leads to a large systematic
error in the predictions for the heavy quarkonium spectrum. The breakdown is a
result of a fine interplay between the short and long distance effects specific
to the lattice regularization of NRQCD. We show how the problem can be solved
within the Schrodinger matching procedure.
