Error Preprocessing => Unknow symbol

Hi there!

I’m a very new Dynare user (I learned how to use it yesterday on the internet if truth be told), and I’m desperately trying to estimate my master’s thesis model.

I always end up with the following message error:
Configuring Dynare …
[mex] Generalized QZ.
[mex] Sylvester equation solution.
[mex] Kronecker products.
[mex] Sparse kronecker products.
[mex] Local state space iteration (second order).
[mex] Bytecode evaluation.
[mex] k-order perturbation solver.
[mex] k-order solution simulation.
[mex] Quasi Monte-Carlo sequence (Sobol).
[mex] Markov Switching SBVAR.

Starting Dynare (version 4.4.2).
Starting preprocessing of the model file …
ERROR: Model_Dyn_1.mod: line 18, cols 16-20: Unknown symbol: alpha

Error using dynare (line 174)
DYNARE: preprocessing failed

although there is no alpha in my code. (There was one, but I replaced it by a the first time I met this error, and it was supposed to be a parameter).
Can someone please tell me what’s wrong in my code?

Thank you very much!
Model_Dyn_1.mod (330 Bytes)

But your model definition, line 18 contains alpha

yd = gam*z*kd^(alpha);