This may be due to the value of unit weight inputted or generation of initial stress field. The aforesaid check may resolve this problem.

Thanks for your response dear Jason. 

It was because of some coding problems.

Dear Mojtaba, I am trying to simulate triaxial test on cylindrical sample for soft soil, and intruppted with same problem.

If you have succed it please give me suggestions.

Dear Bhim

you can add a  '' abs '' before mean pressure calculation in fish code that you can find it in flac manual. 

Thank you very much

Dear Bhim, 

I have encountered -  *** Property bad

could you be able to help me solving the issue please