You will need a 64-bit version of mxDateTime.pyd when used with 64-bit Python. The DLL load fails because a 64-bit process can only load 64-bit DLLs. If you can't get a 64-bit version, it should not be a problem to install and use a 32-bit version of Python on 64-bit Windows (and I generally recommend it - the only thing you gain with 64-bit Python is a higher memory limit). Cheers, Steve -----Original Message----- From: Distutils-SIG [mailto:distutils-sig-bounces+steve.dower=microsoft.com@python.org] On Behalf Of Malte Forkel Sent: Wednesday, June 12, 2013 1010 To: Distutils-Sig@Python.Org Subject: [Distutils] Binary installer on Windows can't install extension Hello, I have a problem with an install script in Python 2.7.5 on Windows 7 64-Bit. I have written an install script to register a COM server for a Windows-specific package. I specify the script with the --install-script option to the bdist_wininst command. When I run the installer, the install script fails trying to install an extension: Traceback (most recent call last): ... File "C:\Program Files\Python\lib\site-packages\mx\DateTime\DateTime.py", line 9, in <module> from mxDateTime import * File "C:\Program Files\Python\lib\site-packages\mx\DateTime\mxDateTime\__init__.py", line 13, in <module> raise ImportError, why ImportError: DLL load failed: %1 is not a valid Win32 application. close failed in file object destructor: sys.excepthook is missing lost sys.stderr The last three lines of output are probably caused by a known, unrelated issue (http://bugs.python.org/issue15321). I can run the install script by hand without problems. Importing mx.DateTime in Python works fine as well. I know very litte about Windows internals, but have a guess nevertheless: I checked mx\DateTime\mxDateTime\mxDateTime.pyd with Dependency Walker (depends.exe). It seems, the extension does not find the proper version of MSVCR90.DLL. Instead, it is trying to use a 32-bit version of the DLL that was installed as part of a 32-bit application. The application's directory is included in the user search path (PATH). Obviously, a 64-bit version of the DLL exists and is used by Python itself. What is causing my problem? How can I solve it? Thanks, Malte _______________________________________________ Distutils-SIG maillist - Distutils-SIG@python.org http://mail.python.org/mailman/listinfo/distutils-sig