toWString() giving me linker errors

[Jared Shapiro]

I am using taglib as a static library on windows.  So far, everything is working, except when i try to get the tag text as a wstring using toWString().  when linking, I get:
 tagReader.obj : error LNK2001: unresolved external symbol "public: class std::basic_string<wchar_t,struct std::char_traits<wchar_t>,class std::allocator<wchar_t> > __thiscall TagLib::String::toWString(void)const " (?toWString at String@TagLib@@QBE?AV?$basic_string at _WU?$char_traits at _W@std@@V?$allocator at _W@2@@std@@XZ)

any ideas on what's causing this, or an alternate way to get either a wstring or an array of wchar_t's?

thanks

jared