Webservice in c++ howto link to old project

[Kristof Thys]

This is what I do:

I create a very simple webservice : new project -> Visual c++ projects
-> ASP.Net web service.

My old project was a c++ application, I change its properties to a dll.
I build it, and add a reference to the web service -> Add reference ->
..NET -> browse for the dll

Then I include the headerfile from the oldproject, where the functions
are I want to call. I call these functions from a wrapper class. (the
wrapperclass is instantiated from the helloworld routine, and I call a
simple function on it wich should return a string)

It compiles and links, but this doesn't seem to work when I invoke the
Helloworld method in my browser.
I think my problem has to do with the following thing:

Suppose I just create a web service template, I add a managedclass.h,
including an header file (testclass.h).
managedclass instantiates testclass and calls a function.
The implementation of this function is in testclass.cpp.
When I compile this, I get an unresolved symbol.
This sort of things always worked when I was programming C++ in VC6...
Maybe my webservice can't find the implementation of my functions in the
old project so he can't handle it.
I've got no clue how to solve this problem...

It's driving me completely crazy...