オブジェクトクラスのArrayListは初期化されません

作成したArrayListを使用してHomeworkDatabaseのクラスを機能させています。私はまだ初心者なので、コードにはおそらく多くのエラーがあります。メインで初期化されていない理由がわかりません。これが私のコードです：

HomeworkDatabase.h：

#ifdef HomeworkDatabase_H
#define HomeworkDatabase_H

class HomeworkDatabase
{
        private:

                string className;
                string homework;
                int dueDate;

       public:

             HomeworkDatabase(string className, string homework, int dueDate);
                HomeworkDatabase();
                string getClass();
                string getHomework();
                int getDueDate();
};

#endif

HomeworkDatabase.cpp：

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

HomeworkDatabase::HomeworkDatabase( string className, string homework, int    dueDate)
{
        this->className = className;
        this->homework = homework;
        this->dueDate = dueDate;
}

HomeworkDatabase::HomeworkDatabase()
{
        this->dueDate = NULL;
}

string getClass::getClass()
{
        return className;
}

string getHomework::getHomework()
{
        return homework;
}

int getDueDate::getDueDate()
{
        return dueDate;

HomeworkArrayList.cpp：

#include <iostream>
#include <string>
#include "HomeworkDatabase.h"

using namespace std;

template <class HomeworkDatabase>
class HomeworkArrayList
{
    private:

            int maxSize;
            int curr;
            int listSize;
            HomeworkDatabase* homework;

    public:

            HomeworkArrayList(int size)
            {
                    maxSize = size;
                    listSize = 0;
                    curr = 0;
                    homework = new HomeworkDatabase[size];
            }

            ~HomeworkArrayList()
            {
                    delete [] homework;
            }

            void append(const HomeworkDatabase& object )
            {
                    homework[listSize] = object;
                    listSize++;
            }

            void frontOfList()
            {
                    curr = 0;
            }

            void backOfList()
            {
                    curr = listSize;
            }

            void prev()
            {
                    curr--;
            }

            void next()
            {
                    curr++;
            }

            int getSize()
            {
                    return listSize;
            }
 }

HomeworkMain.cpp：

#include <iostream>
#include <string>
#include "HomeworkArrayList.cpp"
#include "HomeworkDatabase.h"

using namespace std;

int main()
{
        HomeworkArrayList<HomeworkDatabase> today = HomeworkArrayList<HomeworkDatabase>(50);
        HomeworkDatabase one("Intro to Programming","Read Chapter 1", 12);
        return 0;
}

メインの場合、エラーが発生します。

HomeworkMain.cpp:11:9: error: ‘HomeworkDatabase’ was not declared in this scope
HomeworkMain.cpp:10:43: error: template argument 1 is invalid