The problem of s.d. and t-stat in the result of estimation

deal all

I encountered the followong problem when I estimated the mode, the value of s.d. and t-stat are Inf and zero respectively, why? Can anyone help me on that? I attached my mod file. Thanks ! the version of dynare is 4.0.4, matlab is 7.4.0 (R2007a).

Objective function at mode: -482.688696

RESULTS FROM MAXIMUM LIKELIHOOD
parameters
Estimate s.d. t-stat

     gam   0.0961     Inf  0.0000
   alpha   0.6182     Inf  0.0000
  rho_pi  -0.1339     Inf  0.0000
   rho_y   0.1744     Inf  0.0000
  rho_mu   1.3219     Inf  0.0000
     chi   1.3559     Inf  0.0000
     phi   0.9985     Inf  0.0000
      nu   0.9000     Inf  0.0000
   rho_a   0.2578     Inf  0.0000
   rho_e   0.6853     Inf  0.0000
   rho_x   0.3786     Inf  0.0000
   rho_b  -0.2002     Inf  0.0000

standard deviation of shocks
Estimate s.d. t-stat

     e_r   0.0110     Inf  0.0000
     u_x   0.0874     Inf  0.0000
     u_a  -0.0833     Inf  0.0000
     u_e   0.1655     Inf  0.0000
     u_b   0.0655     Inf  0.0000

Total computing time : 0h03m59s
ciml_nofa.mod (1.67 KB)