Trouble Compiling an OOP Project

Question

I am trying to compile and run an OOP Project but I keep getting 7 LNK2019 Errors everything looks to be defined and linked together. I do not understand why it is not running as it should. I tried running the OOP project in something else besides Visual Studio like CodeBlocks but I also keep getting "Undefined Reference to...". Any help on this topic would be greatly appreciated.

client code:

#include <iostream>
#include <ctime>
#include <cstdlib>
#include <vector>
#include "orderedpair.h"
using namespace std;
using namespace cs_pairs;


int main() {

    int num1, num2;
    OrderedPair<int> myList[10];

    srand(static_cast<unsigned>(time(0)));
    cout << "default value: ";
    myList[0].print();
    cout << endl;

    for (int i = 0; i < 10; i++) {
        myList[i].setFirst(rand() % 50);
        myList[i].setSecond(rand() % 50 + 50);
    }

    myList[2] = myList[0] + myList[1];

    if (myList[0] < myList[1]) {
        myList[0].print();
        cout << " is less than ";
        myList[1].print();
        cout << endl;
    }

    for (int i = 0; i < 10; i++) {
        myList[i].print();
        cout << endl;
    }

    cout << "Enter two numbers to use in an OrderedPair.  Make sure they are different numbers: ";
    cin >> num1 >> num2;
    OrderedPair<int> x;


    x.setFirst(num1);
    x.setSecond(num2);


    cout << "The resulting OrderedPair: ";
    x.print();
    cout << endl;
}

Header Code:

#include <iostream>


namespace cs_pairs 
{
    template <class T>
    class OrderedPair 
    {
    public:

        //static const int DEFAULT_VALUE = int();
        //inline static const T DEFAULT_VALUE = T{};
        static const int DEFAULT_VALUE;

        typedef std::size_t size_type;
        typedef T value_type;

        OrderedPair(value_type newFirst = DEFAULT_VALUE, value_type newSecond = DEFAULT_VALUE);
        void setFirst(value_type newFirst);
        void setSecond(value_type newSecond);
        value_type getFirst() const;
        value_type getSecond() const;
        OrderedPair operator+(const OrderedPair& right) const;
        bool operator<(const OrderedPair& right) const;
        void print() const;

        class DuplicateMemberError
        {

        };

    private:
        value_type first;
        value_type second;
    };

    //template <class T>
    //const int OrderedPair<T>::DEFAULT_VALUE = int();

}

Implementation Code:

#include "orderedpair.h"
#include <iostream>
using namespace std;

namespace cs_pairs {

    template <class T>
    OrderedPair<T>::OrderedPair(value_type newFirst , value_type newSecond) {
        setFirst(newFirst);
        setSecond(newSecond);
    }

    template <class T>
    void OrderedPair<T>::setFirst(value_type newFirst) {
        // if statement to throw an exception if precondition not met goes here.        
        first = newFirst;
    }

    template <class T>
    void OrderedPair<T>::setSecond(value_type newSecond) {
        // if statement to throw an exception if precondition not met goes here.    
        second = newSecond;
    }

    template <class T>
    typename OrderedPair<T>::value_type OrderedPair<T>::getFirst() const {
        return first;
    }

    template <class T>
    typename OrderedPair<T>::value_type OrderedPair<T>::getSecond() const {
        return second;
    }

    template <class T>
    OrderedPair<T> OrderedPair<T>::operator+(const OrderedPair<T>& right) const {
        return OrderedPair(first + right.first, second + right.second);
    }

    template <class T>
    bool OrderedPair<T>::operator<(const OrderedPair<T>& right) const {
        return first + second < right.first + right.second;
    }

    template <class T>
    void OrderedPair<T>::print() const {
        cout << "(" << first << ", " << second << ")";
    }
}