Help: class unresolved symbol building WM5 dll?

I'm trying to use a class from within a dll using c++ VS2005 for WM5:

I declare the class defined in it's own .h and implemented in another cpp
file in the 'main' file as:

static CMyClass* myClass;

then in the DllMains DLL_PROCESS_ATTACH of the same cpp file:

myToday = new CMyClass();

I get a link error: Test.obj : error LNK2019: unresolved external symbol
"public: __cdecl CMyClass::CMyClass()"
(??0CMyClass@@QAA@PAUHINSTANCE__@@PB_W1@Z) referenced in function DllMain

This is driving me mad.... can anyone tell me how to do this?

Thanks
Mark