LNK 2019 error for DLL content

[PeLi]

Hallo everyone,

I have a strange linking problem with VisualStudio 2008:

I have a C++ DLL containing a basic class.
It contains two other classes A and B. Both A and B are
constructed with "new" in the MyClass constructor.
This looks like:

#ifdef MyClass_EXPORTS
#define MyClass_API __declspec(dllexport)
#else
#define MyClass_API __declspec(dllimport)
#endif

class MyClass_API MyClass
{
...
class A_DEF* A ;
class B_DEF* B ;
...
}

I use this DLL in an other C++ project, which is a console
application.

int __cdecl main( int argc, char *argv[] )
{
MyClassDEF* MyClass

MyClass = new MyClassDEF() ;

....

MyClass->A->Function1() ;
MyClass->B->Function2() ;

....
}

What I am struggling with is: B->Funktion2() is not found by the
linker which creates a
LNK2019 error message: "Unresolved external symbol"
At the same time, A->Funktion1() is linked without problem.

I can see no conseptual difference between class A ad B though.
B->Function2() is defined and declared and the compiler has no
problem
with B.

Also, ALL public member variables of B are available, but NONE of its
member functions.

Does anybody have an idea what I am doing wrong?
Thanks in advance, best regards

Peter