COM library and linking error

hello everybody.

i have been thrown into the wonderful world of windows development recently, and although there has been a few stumbling blocks it has been good so far.

i am currently working on a COM library (COM & ATL with VS 2003) it contains several (5) coclasses that each implement a number of different interfaces. to test this library i have a separate vc++ solution in which i use CppUnit to unit test each of the classes. this has been working great so far.

i recently added a utility class to the COM project, which is just a regular c++ class, no COM or ATL magic involved. The Util class works fine from within the project, but when I try to use it in the CppUnit project I get linker errors. It seems as if the Util class is not being made available through the .lilb or dlls that are created by the main project.

I suppose my questions are.
1) Is this approach COM'ish, or is there a better way to create a util class in COM.
2) If this approach is acceptable, do I have to apply some sort of dll magic (or something like that) to make this class available when linking from other projects?

I can provide more explanation if necessary.

a short update.. first i realized i forgot to post the error (doh!)..

Code:

NTDSUtilTestCase.obj : error LNK2019: unresolved external symbol "public: static long __cdecl NTDSUtil::ValidateDTGString(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &)  referenced in function "public: void __thiscall NTDSUtilTestCase::ValidateDTG_ValidDTG(void)" (?ValidateDTG_ValidDTG@NTDSUtilTestCase@@QAEXXZ)
Debug/CPPUnit_Test.exe : fatal error LNK1120: 1 unresolved externals

so. i tried to make the util class a plain ATL object (instead of a plain c++ class), and it gives the same linking error as the plain c++ class..

also, if i move the function definitions to the header file, it links just fine. i am apparently missing something in either linking in the client or in building the util.dll ..

any ideas? anything at all is welcomed, i am new to all this win32-fu..

thanks for your time.