Simulating a MOSFET with silicon nitride as gate dielectric, using semiconductor module

Undefined value found.
- Detail: Undefined value found in the equation residual vector.
There are 24 degrees of freedom giving NaN/Inf in the vector for the variable mod1.N.
at coordinates: (5.84978e-005,-3.33333e-009), (5.84931e-005,-6.66667e-009), (5.12993e-005,-6.66667e-009), (5.13039e-005,-3.33333e-009), (5.03756e-005,-6.66667e-009), ...
There are 24 degrees of freedom giving NaN/Inf in the vector for the variable mod1.P.
at coordinates: (5.84978e-005,-3.33333e-009), (5.84931e-005,-6.66667e-009), (5.12993e-005,-6.66667e-009), (5.13039e-005,-3.33333e-009), (5.03756e-005,-6.66667e-009), ...
There are 24 degrees of freedom giving NaN/Inf in the vector for the variable mod1.V.
at coordinates: (5.84978e-005,-3.33333e-009), (5.84931e-005,-6.66667e-009), (5.12993e-005,-6.66667e-009), (5.13039e-005,-3.33333e-009), (5.03756e-005,-6.66667e-009), ...

While trying to simulate a MOSFET with silicon nitride as the gate dielectric layer, I am getting this error message.
What is the problem here and how to solve it?