error C2079: 'Playlist::PLarray::playlists' uses undefined class Playlist

#include <iostream>
#include <cassert>
#include "style.hpp"
#include "Playlist.hpp"
 
 
class PLarray
	{
	public:
		PLarray()
		//creates this PLarraywith the default values
			{}
 
		~PLarray()
		//destroys this PLarray object
			{std::cout << "In ~PLArray()";}
 
		const Playlist operator [] (unsigned IN location) const;
		//returns a specified playlist
 
		Playlist& operator [] (unsigned IN location);
		//returns access to a specified playlist
 
		enum {capacity = 10};
 
		///***
	private:
		Playlist playlists[capacity];
 
	};
#endif

#include "PLArray.hpp"
#include <cassert>
 
 
using namespace std;
 
 
 
 
const Playlist PLarray:: operator [] (unsigned location) const
	{  assert (location < capacity); 
	return playlists [location]; 
	}
 
Playlist& PLarray:: operator [] (unsigned location)
	{  assert (location < capacity); 
	   return playlists [location]; 	
 
	}