Is the excessive use of the Derivative block the cause of my problem ??

Hi everyone,

I built a simulink model in which I was obliged to use the derivative block many times. But each time I run the simulation it stops and I have the error message below:

a =
    0.2831
a =
   1.0298e+11
a =
   4.8985e+30
a =
   1.0973e+89
An error occurred while running the simulation and the simulation was terminated
Caused by:
Error in 'board_with_derivatives/calculation of Y_0_dd /Interpreted MATLAB Function'. Evaluation of expression resulted in an invalid output. Only finite double vector or matrix outputs are supported

Also I used the unit delay block many times in order to break the algebraic loops.

I have attached to this question the simulink model and the m-file containing the necessary parameters for running the simulation.

Any help is appreciated.

Thank you very much in advance.