error MEMS

Hi Ivan sorry if I am contacting you but I need help.
I have problems with the attached exercise.
The error that appears is
"Failed to find a solution:
In segregated group 1: The relative residual (0) is greater than the relative tolerance.
Returned solution has not converged."
I don't know what is wrong.
Can you help me please??
Sorry to bother you.
Francesca