C++: Is there a way with templates to overload << to do a no-op on a certain class specialization?

My class N takes a type T and a varying amount of types F...

What's really happening is that I am overloading operator() to take a function reference and the arguments that that function will be supplied. It's like a bind function. But when the function reference returns void, I don't want to be able to std::cout the value of that function call from operator(). So I added an overload of operator<< for std::cout to NOT do anything but I guess I'm not writing out the function signature correctly because I get the same errors. Does anyone know what I'm doing wrong?

    #include <iostream>

    #include <utility>

    template <typename T>

    struct N;

    template <typename T, typename ... F>

    struct N<T(F...)> {

        T operator()(T (&t)(F...), F&&... f) {

            return t(std::forward<F>(f)...);

        }

    };

    template <typename ... T> void operator<< (std::ostream &, const N<void(T...)> &) {}

    void f(int, int) {}

    int main() {

        N<void(int, int)> bind;

        std::cout << bind(f, 5, 4);

    }

Here's a demo -- http://ideone.com/t5eK7d#view_edit_box

The above code fails because I'm printing out a function that returns void; and that is the function f. My overload of operator<< doesn't seem to be affecting anything. If you need any more detail just say so. Thanks.