MPI_Get failed in fortran [Please help me]

I just used mpi one-sided communication to write a simple demo, which is process 1 just fetch an integer from process 0.

here is the code

program main
    include "mpif.h"
    integer a(10), b(10)
    integer :: myid, numprocs, ierr
    integer :: win, data_win
    integer :: k, p
    integer size_of_window

    call MPI_INIT(ierr)
    call MPI_Comm_rank(MPI_COMM_WORLD, myid, ierr)
    call MPI_Comm_size(MPI_COMM_WORLD, numprocs, ierr)

    !print*, win
    if (myid .eq. 0) then
        call mpi_win_Create(a, 4*10, 4, mpi_info_null, MPI_COMM_WORLD,win,ierr)
    else
        call mpi_win_Create(null, 0, 1, mpi_info_null, MPI_COMM_WORLD,win,ierr)
    endif
    print*, win

    if (myid .eq. 0) then
        do i=1,10
            a(i) = 99
        enddo
    endif

    if(myid .ne. 0) then
        !print*, win
        call MPI_Win_lock(MPI_LOCK_SHARED,0,0,win,ierr)
        call MPI_Get(b,10,mpi_integer,0,0,10,mpi_integer,win,ierr)
        call MPI_Win_unlock(0,win,ierr)
        print *,"err", ierr

        call MPI_Win_free(win, ierr)
        print *,"myid ", myid, "get message", b
    else
        !print*, win
        call MPI_Win_free(win, ierr)
    endif
    call MPI_Barrier(MPI_COMM_WORLD, ierr)
end program

but it doesn't work at all, I try so many ways it just don't reach the print message line, please can someone tell me what's going on