I really need help!!! about argtypes and restype I think..

[Yuji3131]

Recently Ive tried using Fortran subroutine with ctypeps in Python

the question is how can I send array to fortran?
here are my Fortran code and python code.

subroutine add_array(a,b,N)
    implicit none
    real(8),dimension(0:1024),intent(in) :: a
    real(8),dimension(0:1024),intent(inout):: b
    integer(8),intent(in) :: N  
    
    if (N.LT.1024) then
        write(*,*) "Maxsize is too small."
    end if
    b(0:N-1) = b(0:N-1) + a(0:N-1)
end subroutine
stop
end

---

#!/usr/bin/env python
#vim:fileencoding=utf8
from ctypes import *
import numpy as np

add_np = cdll.LoadLibrary("C:\\Users\\Owner\\Desktop\\Forpython\\add_np\\add_np\\add_np\\Debug\\add_np.dll")

add_np.add_array_.argtypes = [
               np.ctypeslib.ndpointer(dtype=np.float64),#a
               np.ctypeslib.ndpointer(dtype=np.float64),#b
               POINTER(c_int64),]                       #N

add_np.add_array_.restype = c_void_p   #b

a = np.arange(0.,10.,dtype=np.float64) # 0,1,2,3,4,5,..,9 
b = a*2                                # 0,2,4,6,8,...,18
N = byref(c_int64(b.N)) 
add_np.add_array_(byref(a),byref(b),byref(N)) 
print b # [ 0 3 6 9 12 .. 27 ]

but Python message is 

Error:
Traceback (most recent call last):
  File "C:\Users\Owner\Desktop\Forpython\add_np\add_np.py", line 11, in <module>
    POINTER(c_int64),]                       #N
  File "C:\Python27\lib\ctypes\__init__.py", line 375, in __getattr__
    func = self.__getitem__(name)
  File "C:\Python27\lib\ctypes\__init__.py", line 380, in __getitem__
    func = self._FuncPtr((name_or_ordinal, self))
AttributeError: function 'add_array_' not found

and are these codes right?
could you help me please!!
thanks..