python调用VS2005编译的动态库出现问题

各位大牛好，用python调用vs2005编译的动态库是遇到问题，描述如下：
python脚本：
def test_fun(a):
print "in test_fun windll mode"
hNet=windll.LoadLibrary("testdll.dll")
nret1=hNet.test_fun(a)
print "nret1="+str(nret1)
return

python中出现的错误说明为：
Traceback (most recent call last):
File "<pyshell#1>", line 1, in <module>
test_fun(2)
File "D:\mywork\test\testpy\bin\pytest.py", line 47, in test_fun
hNet=windll.LoadLibrary("testdll.dll")
File "D:\Python27\lib\ctypes\__init__.py", line 443, in LoadLibrary
return self._dlltype(name)
File "D:\Python27\lib\ctypes\__init__.py", line 365, in __init__
self._handle = _dlopen(self._name, mode)
WindowsError: [Error 1114] 动态链接库(DLL)

请各位python高手帮忙看看，该怎么解决？先谢谢了！！