Difference between mpicc and mpiicc

I write a simple mpi program as follow:

#include "mpi.h"

#include <stdio.h>

#include <math.h>

void main(argc,argv)

int argc;

char *argv[];

{

    int myid,numprocs;

    int namelen;

    char pro_name[MPI_MAX_PROCESSOR_NAME];

    MPI_Init(&argc,&argv);

    MPI_Comm_rank(MPI_COMM_WORLD,&myid);

    MPI_Comm_size(MPI_COMM_WORLD,&numprocs);

    MPI_Get_processor_name(pro_name,&namelen);

    printf("Process %d of %d on %s\n",myid,numprocs,pro_name);

    MPI_Finalize();

}

When I compile it with "mpicc -o xxx xxx.c" and run it with "mpirun -np 8 ./xxx", it rightly creates 8 processes. But when I compile it with "mpiicc -o xxx xxx.c" and run with the same order as above, it only creates 1 process. I want to know what's the difference between the mpicc and mpiicc. Is it caused by some faults made during my installment? And how can I fix it? By the way, I install the impi and compiler of intel by installing the intel cluster studio (l_ics_2013.1.039_intel64).

Here is the result:

[root@localhost test]# mpicc -o mpitest mpi-test.c

[root@localhost test]# mpirun -np 8 ./mpitest 

Process 3 of 8 on localhost.localdomain

Process 4 of 8 on localhost.localdomain

Process 5 of 8 on localhost.localdomain

Process 6 of 8 on localhost.localdomain

Process 7 of 8 on localhost.localdomain

Process 0 of 8 on localhost.localdomain

Process 1 of 8 on localhost.localdomain

Process 2 of 8 on localhost.localdomain

[root@localhost test]# mpiicc -o mpitest mpi-test.c

[root@localhost test]# mpirun -np 8 ./mpitest 

Process 0 of 1 on localhost.localdomain

Process 0 of 1 on localhost.localdomain

Process 0 of 1 on localhost.localdomain

Process 0 of 1 on localhost.localdomain

Process 0 of 1 on localhost.localdomain

Process 0 of 1 on localhost.localdomain

Process 0 of 1 on localhost.localdomain

Process 0 of 1 on localhost.localdomain