Number of mixed variables oo_.dr.nboth=1

Anybody can help? I did not understand why dynare tell me there are one mixed variable in the model after running the model file since oo_.dr.nboth=1?
It seems that there are no mixed variables in the model.
mixed variables are those that appear at current, past and future period in the model (i.e. at t, t+1 and t-1). The number of such variables is stored in oo_.dr.nboth.

[code]var c k lab z;
varexo e;

parameters bet the del alp tau rho s;

bet = 0.987;
the = 0.357;
del = 0.012;
alp = 0.4;
tau = 2;
rho = 0.95;
s = 0.007;

model;
(c^the*(1-lab)^(1-the))^(1-tau)/c=bet*((c(+1)^the*(1-lab(+1))^(1-the))^(1-tau)/c(+1))(1+alpexp(z(+1))k^(alp-1)lab(+1)^(1-alp)-del);
c=the/(1-the)
(1-alp)exp(z)k(-1)^alplab^(-alp)(1-lab);
k=exp(z)k(-1)^alplab^(1-alp)-c+(1-del)k(-1);
z=rho
z(-1)+s
e;
end;

initval;
k = 1;
c = 1;
lab = 0.3;
z = 0;
e = 0;
end;

shocks;
var e;
stderr 1;
end;

steady;

stoch_simul(periods=1000,irf=40,simul_seed=123456,order=2);[/code]