Derivative of state '1' in block 'prot_2/LTI System/Internal' at time 0.50009 is not finite?

Hi!

after deriving tthis trasnfer function I got this error in simulink, my stap size start at 0.5s:

An error occurred while running the simulation and the simulation was terminated

Caused by:

• Derivative of state '1' in block 'prot_2/LTI System/Internal' at time 0.50009 is not finite. The simulation will be stopped. There may be a singularity in the solution. If not, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances)
• my transfert function is:
• -2.772e-15 s^3 - 5.898e-10 s^2
• ---------------------------------------------------------
• 1.241e-29 s^4 - 8.436e-17 s^3 - 7.033e-08 s^2 - 0.01496 s