Problems with 64-bit ISAPI Extensions

Greetings,

I posted this to isapi-dev too, but since I could have a
glitch on IIS configuration which is causing my problems,
I will post this here too. Sorry for multi-post.

I have big problem getting 64-bit ISAPI extensions to work
on Windows 2003 Server 64-bit.

My 64-bit compiling & linking environment is otherwise
producing fine 64-bit executables, but I cannot get even
the simpliest ISAPI extension to run.

I have tested with non-MFC ISAPI-extensions too, with no
success, but currently I am trying to get MFC ISAPI
Extension to work properly.

IIS calls GetExtensionVersion and TerminateExtension
properly, but everything else fails.

With incorrect function name, the result is "BAD REQUEST,
Your client sent a request that this server didn't
understand. Request: " (error 400)

Strange thing is that there is nothing after "Request: "
I tested with 32-bit IIS and the same DLL (32-bit version)
returned the incorrect function name after "Request:", for
example: "Request: somefunctio"

When using correct function name, the result is
always "SERVER ERROR, The server encountered an internal
error or misconfiguration and was unable to complete your
request." (error 500)

I cannot find anything useful from eventlog or IIS-log.
IIS-log only tells me the same error codes, no sc-win32-
status-code.

My "scripts"-directory has proper permissions set from IIS
Manager, and IUSR_-account has proper permissions to
directory and the files. Also, permissions from Web
Service Extensions has been configured properly (tried
specifying the dll:s explicitly, and Allowing All unknown
ISAPI Extensions).

I am running IIS on Worker Process Model (not IIS 5.0).
The computer with 64-bit W2K3 is HP RX2600. At first I
compiled on the same machine, but now I am compiling the
software on 32-bit W2K professional.

I have tried many different configurations and settings. I
have tried to find errors on my compiling environment
(executables compile fine) but I am starting to run out of
ideas.

My platform SDK is the latest (with 64-bit headers,
libraries and redistributables). MFC and other needed
DLL:s are properly installed on the machine.

I also have tried compiling with both VS6, and VS.NET
(thru devenv.exe). Both produced fine 64-bit executables,
and 32-bit ISAPI Extensions, but none of the 64-bit ISAPI
Extensions worked.

What am I missing here?

Petri Simolin
Software Engineer
Database Administrator
Systems Administrator