XCode's C++ Linker and "Symbol Not Found"

Question

I'm having trouble with the C++ Linker and it might have to do with how my project is set up:
Right now, I'm developing a simple C++ (command-line) problem in XCode 3.2.6, and while my sources compile, I'm getting a series of weird errors.  Upon closer inspection, it appears that the "symbol not found" errors all relate to code in a file code.cpp, which calls functions declared in util.h, and for which the functions are declared in util.cpp; it appears that the object file code.o cannot find the symbols generated from util.o.  How do I fix this?

Answer 1

Alright.  A little bit more concrete than what I had before:  First the "symbol not found" error:
"std::set<unsigned long, std::less<unsigned long>, std::allocator<unsigned long> > setIntersection<unsigned long>(std::set<unsigned long, std::less<unsigned long>, std::allocator<unsigned long> > const&, std::set<unsigned long, std::less<unsigned long>, std::allocator<unsigned long> > const&)", referenced from:
AnchorSet::evaluate(std::set<unsigned long, std::less<unsigned long>, std::allocator<unsigned long> > const&) constin AnchorSet.o
AnchorSet::evaluate() is declared in AnchorSet.h and defined in AnchorSet.cpp.  setIntersection() is declared in utils.h and defined in utils.cpp.
In AnchorSet.h:
class AnchorSet {
  public:
                    unsigned long evaluate(const Subset& B) const;
In utils.h:
template<class T>
std::set<T> setDifference(const std::set<T>& A, const std::set<T>& B);
Any specific code that is needed beyond this?