Calling function in EXE from DLL

I'm trying to use an pointer to a base class in a dll passed in by the
exe. In VC7 I keep getting runtime exception relating to how the
"function pointer" was declared. Can someone help?

It seems that this would be a very common thing to do.

I'm not sure I've found the right news group, sorry if I haven't.

What I'm doing is:

dll.h:
class __declspec(dllexport) CVirtualBaseClass
{
public:
virtual bool func1() = 0;
};

__declspec(dllexport) void DoSomethingWithObject(CVirtualBaseClass*
pVBC);

dll.cpp:
void DoSomethingWithObject(CVirtualBaseClass* pVBC)
{
pVBC->func1(); //this get's exception upon return.
}

exe.cpp:
#include dll.h
class CImplementation : public CVirtualBaseClass
{
public:
virtual bool func1()
{
return true;
}
};

void DoSomethingWithDll
{
DoSomethingWithObject(new CImplementation);
}

Thanks,
Andy