pymysql.err.InternalError: (1236, u'Could not find first log file name in binary log index file')

from pymysqlreplication import BinLogStreamReader

MYSQL_SETTINGS = {
"host": "127.0.0.1",
"port": 3306,
"user": "root",
"passwd": ""
}
def main():
stream = BinLogStreamReader(connection_settings=MYSQL_SETTINGS,
server_id=610,
log_file="/u02/mysql/mysql-bin.000012",
log_pos=23569311)
for binlog_event in stream:
binlog_event.dump()
stream.close()

if **name** == "**main**":
## main()

Traceback (most recent call last):
File "mysql_binlog_dump.py", line 28, in
main()
File "mysql_binlog_dump.py", line 23, in main
for binlog_event in stream:
File "/usr/lib/python2.6/site-packages/pymysqlreplication/binlogstream.py", line 243, in fetchone
pkt = self._stream_connection._read_packet()
File "/usr/lib64/python2.6/site-packages/pymysql/connections.py", line 826, in _read_packet
packet.check_error()
File "/usr/lib64/python2.6/site-packages/pymysql/connections.py", line 373, in check_error
raise_mysql_exception(self.__data)
File "/usr/lib64/python2.6/site-packages/pymysql/err.py", line 117, in raise_mysql_exception
_check_mysql_exception(errinfo)
File "/usr/lib64/python2.6/site-packages/pymysql/err.py", line 113, in _check_mysql_exception
raise InternalError(errno, errorvalue)
pymysql.err.InternalError: (1236, u'Could not find first log file name in binary log index file')

why output this error?