Hello Haider,
Are you compiling mpich and installing it in a global path accessible to all machines or you are using local installations? The missing symbol is a fortran symbol. The fact it is not there can mean mpich was not compiled with fortran support while
your application is a fortran code. The fact that it works for a certain number of processes might mean some machine do have fortran support while other machines don’t.
Can you provide some additional information about your cluster configuration? The MPICH version you are running and how you are configuring it?
--Giuseppe