the final mle estimates are :
coefficient standard-error t-ratio
beta 0 0.39417113E+01 0.99583894E+00 0.39581815E+01
beta 1 0.62797349E+00 0.94595508E-01 0.66385128E+01
beta 2 -0.93342975E-03 0.18648289E-01 -0.50054445E-01
beta 3 -0.43396828E-01 0.32271221E-01 -0.13447532E+01
sigma-squared 0.25709726E-02 0.81616171E-03 0.31500775E+01
gamma 0.28495349E-04 0.70299417E-01 0.40534260E-03
mu is restricted to be zero
eta is restricted to be zero
log likelihood function = 0.34381678E+02
the likelihood value is less than that obtained
using ols! - try again using different starting values