BK condition fails for initial_estimation_checks but works for stoch_simul

Dear all,
I have a question when dealing with Bayesian estimation.
In the .mod file, I have stoch_simul() part before the estimation() command, and I set

estimated_params_init(use_calibration);
end;

in front of estimation() command.

It reports BK condition fails error for estimation() command but the initial stoch_simul() part pass it.

The error message is as follows,

ESTIMATION_CHECKS: There was an error in computing the likelihood for initial parameter values.
ESTIMATION_CHECKS: If this is not a problem with the setting of options (check the error message below),
ESTIMATION_CHECKS: you should try using the calibrated version of the model as starting values. To do
ESTIMATION_CHECKS: this, add an empty estimated_params_init-block with use_calibration option immediately before the estimation
ESTIMATION_CHECKS: command (and after the estimated_params-block so that it does not get overwritten):


Error using print_info
Error using print_info
Blanchard & Kahn conditions are not satisfied: no stable equilibrium.

Error in initial_estimation_checks (line 248)
        print_info(info, options_.noprint, options_)

Error in dynare_estimation_1 (line 165)
    oo_ = initial_estimation_checks(objective_function,xparam1,dataset_,dataset_info,M_,estim_params_,options_,bayestopt_,bounds,oo_);

Error in dynare_estimation (line 105)
    dynare_estimation_1(var_list,dname);

Error in ModelBayesianEstimationRoots.driver (line 663)
oo_recursive_=dynare_estimation(var_list_);

Error in dynare (line 308)
    evalin('base',[fname '.driver']);

Error in rundynare (line 14)
 dynare ModelBayesianEstimationRoots.mod

I am really confused about this situation. I was wondering why the BK condition fails for the initial estimation checks even if the calibration of parameters in the simulation works.

Thank you very much!

Often that is because the model has a unit root and you forgot to use diffuse_filter.

Professor, thank you so much!
The code works now.