[RESOLVED] Error - "undefined class"

[vutives]

Hi everyone. I'm fighting with this thing since yesterday and can't get any idea what's wrong. Here's the code of my Headquarters.h:

#ifndef HEADQUARTERS_H
#define HEADQUARTERS_H
#include "node.h"
#include "Main_trucks_list.h"    //Isn't it defined here?
#include "Main_firefighters_list.h"    //And here?
#include <string>

using namespace std;

class Firebrigade;
class Accident;
class Main_trucks_list; 
class Main_firefighters_list;

class Headquarters
{
private:
	Main_trucks_list my_main_trucks_list;  //ERROR HERE
	Main_firefighters_list my_main_firefighters_list;   //ERROR HERE
	node<Accident>* accident_head;	
	node<Firebrigade>* firebrigade_head;	
	string town;
	string street;
	friend class Accident;
	friend class Firebrigade;
	friend class Firefighter;
	friend class Truck;

public:
	node<Firebrigade>* get_firebrigade_head() const;	
	bool insert_firebrigade(Firebrigade*);			
	bool delete_firebrigade(string address);		
	bool create_accident(string place, unsigned how_many_firefighters);		
	unsigned count_accidents() const;				
	bool remove_accident(unsigned id);				
	void display_accidents() const;					
	Headquarters(string town, string street);		
	~Headquarters();						
};

#endif

The errors:

Error	1	error C2079: 'Headquarters::my_main_trucks_list' uses undefined class 'Main_trucks_list'	c:\users\pawel\desktop\c++ project\fire brigade\fire brigade\headquarters.h	20

Error	2	error C2079: 'Headquarters::my_main_firefighters_list' uses undefined class 'Main_firefighters_list'	c:\users\pawel\desktop\c++ project\fire brigade\fire brigade\headquarters.h	21

I can't understand why I get that. In lines 12 and 13 I declared the classes which are defined in their headerfiles. What's the problem?


Additional:

Main_trucks_list.h:

#pragma once
#include "Truck.h"

class Truck;

class Main_trucks_list
{
private:
	node<Truck>* head;

public:
	bool insert_truck(Truck*);
	bool remove_truck(unsigned id);
	Main_trucks_list(void);
	~Main_trucks_list(void);
	Truck* find(unsigned id) const;
};

Main_firefighters_list.h:

#pragma once
#include "Firefighter.h"

class Firefighter;

class Main_firefighters_list
{
private:
	node<Firefighter>* head;

public:
	bool insert_firefighter(Firefighter*);
	bool remove_firefighter(unsigned id);
	Main_firefighters_list(void);
	~Main_firefighters_list(void);
	Firefighter* find(unsigned id) const;
};

Please, help me, I'm going crazy...