Starting Dynare (version 4.4.0).
Starting preprocessing of the model file …
Ramsey Problem: added 14 Multipliers.
Found 14 equation(s).
Found 29 FOC equation(s) for Ramsey Problem.
Evaluating expressions…done
Computing static model derivatives:

order 1
Computing dynamic model derivatives:

order 1

order 2
Computing static model derivatives:

order 1

??? Error using ==> dynare at 156
DYNARE: preprocessing failed[/code]

any ideas whats going wrong ?
I dont only get that error but also Dynare crashes, stating “dynare_m.exe does not work anymore”

I dont wanna open a new topic for this questions althought it is not related to the error above (however it is related to Ramsey optimal policy):

Is there a way to constraint the instrument used for the optimal policy exercise to be positive?
I am trying to replicate a paper’s IRFs (which works quite well for the basecase) but so far not for the optimal policy part.

One source for the differences might be that Dynare suggests a path for the instrument that involves negative values (althought this does not make sense from an economic point of view). How can I prevent that ? (or cant I since I am in a stochastic model and I cant use e.g. a max{}-operator due to local approximations ?)

(btw:
-since I used exp() in my model in order to loglinearize, I enter the variables as well with exp() into the objective function, no?
-including an endogenous variable that is following an AR(1) which innovation is getting shocked into the planner’s objective should not be an issue, should it?)