Determnistic Model does not return to steady state

Dear all,
my model does not return to the values which dynare itself has calculated to be the steady state values and which I have checked by hand myself. Specifying more periods does not help: the simulation literally converges to a value which is different from the steady state value, and only starts to converge during the last few periods. Is there anything I can do to solve the problem? Many Thanks?
Best,
Ansgar