I'm having compiler errors, and I'm not sure why. What am I doing wrong here:
Hangman.cpp:
set<char> Hangman::incorrectGuesses()
{
     // Hangman line 103
    return Utils::findAll_if<char>(guesses.begin(), guesses.end(), &Hangman::isIncorrectGuess);
}
bool Hangman::isIncorrectGuess(char c)
{
    return correctAnswer.find(c) == string::npos;
}
Utils.h:
namespace Utils
{
    void PrintLine(const string& line, int tabLevel = 0);
    string getTabs(int tabLevel);
    template<class result_t, class Predicate>
    std::set<result_t> findAll_if(typename std::set<result_t>::iterator begin, typename std::set<result_t>::iterator end, Predicate pred)
    {
        std::set<result_t> result;
              // utils line 16
        return detail::findAll_if_rec<result_t>(begin, end, pred, result);
    }
}
namespace detail
{
    template<class result_t, class Predicate>
    std::set<result_t> findAll_if_rec(typename std::set<result_t>::iterator begin, typename std::set<result_t>::iterator end, Predicate pred, std::set<result_t> result)
    {
              // utils line 25
        typename std::set<result_t>::iterator nextResultElem = find_if(begin, end, pred);
        if (nextResultElem == end)
        {
            return result;
        }
        result.insert(*nextResultElem);
        return findAll_if_rec(++nextResultElem, end, pred, result);
    }
}
This produces the following compiler errors:
    algorithm(83): error C2064: term does not evaluate to a function taking 1 arguments
    algorithm(95) : see reference to function template instantiation '_InIt std::_Find_if<std::_Tree_unchecked_const_iterator<_Mytree>,_Pr>(_InIt,_InIt,_Pr)' being compiled
    1>          with
    1>          [
    1>              _InIt=std::_Tree_unchecked_const_iterator<std::_Tree_val<std::_Tset_traits<char,std::less<char>,std::allocator<char>,false>>>,
    1>              _Mytree=std::_Tree_val<std::_Tset_traits<char,std::less<char>,std::allocator<char>,false>>,
    1>              _Pr=bool (__thiscall Hangman::* )(char)
    1>          ]
utils.h(25) : see reference to function template instantiation '_InIt std::find_if<std::_Tree_const_iterator<_Mytree>,Predicate>(_InIt,_InIt,_Pr)' being compiled
    1>          with
    1>          [
    1>              _InIt=std::_Tree_const_iterator<std::_Tree_val<std::_Tset_traits<char,std::less<char>,std::allocator<char>,false>>>,
    1>              _Mytree=std::_Tree_val<std::_Tset_traits<char,std::less<char>,std::allocator<char>,false>>,
    1>              Predicate=bool (__thiscall Hangman::* )(char),
    1>              _Pr=bool (__thiscall Hangman::* )(char)
    1>          ]
utils.h(16) : see reference to function template instantiation 'std::set<_Kty> detail::findAll_if_rec<result_t,Predicate>(std::_Tree_const_iterator<_Mytree>,std::_Tree_const_iterator<_Mytree>,Predicate,std::set<_Kty>)' being compiled
    1>          with
    1>          [
    1>              _Kty=char,
    1>              result_t=char,
    1>              Predicate=bool (__thiscall Hangman::* )(char),
    1>              _Mytree=std::_Tree_val<std::_Tset_traits<char,std::less<char>,std::allocator<char>,false>>
    1>          ]
hangman.cpp(103) : see reference to function template instantiation 'std::set<_Kty> Utils::findAll_if<char,bool(__thiscall Hangman::* )(char)>(std::_Tree_const_iterator<_Mytree>,std::_Tree_const_iterator<_Mytree>,Predicate)' being compiled
    1>          with
    1>          [
    1>              _Kty=char,
    1>              _Mytree=std::_Tree_val<std::_Tset_traits<char,std::less<char>,std::allocator<char>,false>>,
    1>              Predicate=bool (__thiscall Hangman::* )(char)
    1>          ]