Windows Python多播上的错误10049

import socket,struct

ADDR='239.239.250.1'
PORT=8001

sock = socket.socket(socket.AF_INET,socket.SOCK_DGRAM)
sock.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)
sock.bind((ADDR,PORT))
mreq = struct.pack("4sl",socket.inet_aton(ADDR),socket.INADDR_ANY)
sock.setsockopt(socket.IPPROTO_IP,socket.IP_ADD_MEMBERSHIP,mreq)

但在Windows上运行时在绑定上收到错误10049.

Z:winx>c:Python27python.exe q2.py
Traceback (most recent call last):
  File "q2.py",line 11,in <module>
    sock.bind((ADDR,PORT))
  File "c:Python27libsocket.py",line 224,in meth
    return getattr(self._sock,name)(*args)
socket.error: [Errno 10049] The requested address is not valid in its context

Windows多播是否存在已知问题？如果没有,我可以采取哪些步骤进行诊断？