I think I've overridden a virtual method but I'm still getting: "X must implement the inherited pure virtual method Y"

I am attempting to implement an interface in C++ for a game that I am writing and I am running in an error. Here is the interface and its subclass that I created: ``` //Attack.h //defines a set of values associated with all attacks //and an interface for all attacks typedef unsigned const int attack_type; typedef unsigned const int p_attack_type; //defines the attack types static const attack_type NORMAL = 0; static const attack_type ADDER = 1; static const attack_type MULTIPLIER = 2; static const attack_type AREA_OF_EFFECT = 3; static const attack_type DAMAGE_OVER_TIME = 4; static const attack_type STATUS = 5; //String representation of the names of attack types static std::string attack_types [] = {"Normal","Adder","Multiplier","Area-Of-Effect","Damage-Over-Time","Status"}; class Attack { protected: std::string attack_name;//the name of this attack attack_type type;//the type of attack this represents int cool_down_turns;//represents the number of turns this ability cannot be used after being used bool causesGlobalCooldown;//does this attack cause ALL abilities to cooldown -- during combat should force cooldown on everything bool on_cool_down; public: Attack(std::string name, attack_type, int cooldown_t, bool causesGlobalCooldown = false) { this->attack_name = name; this->type = attack_type; this->causesGlobalCooldown = causesGlobalCooldown;//whether or not ALL abilities need to cooldown this->cool_down_turns = cooldown_t;//amount of turns that cooldown occurs this->on_cool_down = false;//whether or not this attack is on cooldown } //the main method called to perform this attack //calculate damage, calculate cooldown -- for spells calculate cost //return the amount of damage this attack does virtual int do_attack(int modifier, int roll) { //calculate damage int damage = calculate_damage(modifier,roll); //check cooldown if(this->cool_down_turns>0) { this->cooldown(true); } return damage; } //defined by sub classes -- useful to tell you how much damage the attack is going to do virtual int calculate_damage(int modifier, int roll) = 0; //**standard method definitions**// //get the attack name std::string get_attack_name() const { return this->attack_name; } //get the attack type attack_type get_attack_type() const { return this->type; } //get the attack type name of this attack std::string get_attack_type_name() const { return attack_types[this->type]; } //check the cooldown status of this attack bool cooldown() const { return on_cool_down; } //set the cooldown status of this attack void cooldown(bool set) { this->on_cool_down = set; } }; ``` Here is the subclass : ``` /* * Normal.cpp * * Created on: Jul 15, 2012 * Author: christian * Standard Definition of a Normal attack */ #include "Attack.h" class Normal : public Attack { public: Normal(std::string name) { Attack(name,NORMAL); } int calculate_damage(int modifier, int roll) const { return roll + modifier; } }; ``` The error being returned from the compiler is : The type 'Attack' must implement the inherited pure virtual method 'Attack::calculate_damage' Does anyone know the correct syntax for this? Do I have the inheritance setup correctly?