You are referring to objects which are not defined. Dynare does not know what “ce_ss” and the other “_ss” terms are without you telling it. I suppose these are the coefficients from linearizing your nonlinear model around its non-stochastic steady state, which are necessarily functions of the steady state values for the endogenous variables. You must calculate those somehow, either analytically or numerically.
See the Dynare Reference Manual’s section on Model Declaration and Steady State, the discussion on the Dynare forums here, or Pfeifer (2018) A Guide to Specifying Observation Equations for the
Estimation of DSGE Models available here.