cx_Oracle:Unable to acquire Oracle environment handle issue

jordanking1980

OS:Win 7 64bit
Python: 2.7 64 bit
Instant client: instantclient-basic-windows.x64-11.2.0.3.0
cx_Oracle: cx_Oracle-5.1.2-11g.win-amd64-py2.7.msi
DB server: Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production

Instant client安装在C:\Oracle\instantclient_11_2

oci.dll拷贝到C:\Python27\Lib\site-packages

环境变量设置：
ORACLE_HOME=C:\Oracle\instantclient_11_2
TNS_ADMIN=C:\Oracle\network\admin
Path=C:\Oracle\instantclient_11_2;C:\Python27;...

用Sqlplus可以成功登陆


Scripts:
import cx_Oracle

con = cx_Oracle.connect('cbs_owner/comverse@//10.230.22.95:1521/cust1_svc')
print con.version

con.close()

Error Information：

Traceback (most recent call last):
  File "C:\Users\gongnianshu.CNT01\Desktop\Oracle.py", line 15, in <module>
    con = cx_Oracle.connect('cbs_owner/comverse@//10.230.22.95:1521/cust1_svc')
cx_Oracle.InterfaceError: Unable to acquire Oracle environment handle
[Finished in 0.3s with exit code 1]