Make class hidden from project

[JohnnyKPL]

I have a dll project and many classes on it. It's something like that:

namespace x
{
   class A {};

   __declspec(dllexport) class B : public A {};

   __declspec(dllexport) class C : public A {};
}

When I export the library and import it on another project I see all the classes: x::A, x::B and x::C. But when I try to make an instance of the class A it give me an error: unknown identifier.
It's because I doesn't put __declspec(dllexport) declaration before the class A.
So is there any way to make A hidden from the project???
Or, I have to make a class witch contains all of them and set 'A' as a private class?

[helios]

If the error is unknown identifier rather than some undefined reference, then it sounds like A is already hidden, since the compiler doesn't seem to understand what 'A' in new A is. What's probably happening is that your IDE's autocomplete function can see the other project and is suggesting types that aren't visible from the current project.