GIF file isn't showed in Tkinter canvas even though it is not garbage collected?

I am creating a game with Tkinter. I created a chess-board and I wanted to add the pieces in the board. However, when I add the image it doesn't appear.

I DID read about the garbage-collector issue and tried different things. For example making the image a global or to make it a class variable.

This is my code:

import tkinter as tk

LARGE_FONT = ("Verdana", 12)
WIDTH = 1200
HEIGHT = 750
AREA_WINDOW = str(WIDTH)+"x"+str(HEIGHT)  # 1200x700


class Application(tk.Tk):

    def __init__(self, *args, **kwargs):
        # *args = arguments. Pass as many variables as you want
        # kwargs = keyword arguments. Pass dictionaries.

        tk.Tk.__init__(self, *args, **kwargs)  # Let's initialize tkinter.

        container = tk.Frame(self)  # It will contain everything of the app.
        container.pack(side="top", fill="both", expand="True")
        # Fill tells the widget to grow to as much space is available for it in the direction specified
        # BOTH means that the widget should expand both horizontally and vertically
        # The expand is beyond the limits that you gave, while fill is the limits you said.

        container.grid_rowconfigure(0, weight=1)  # Weight 2 will grow twice as 1
        container.grid_columnconfigure(0, weight=1)  # We want equal so we leave at 1.

        self.frames = {}  # Empty dictionary.

        for Frame in (StartPage, Game):

            frame = Frame(container, self)
            self.frames[Frame] = frame
            frame.grid(row=0, column=0, sticky="nsew")  # Align and stretch everything to the sides of the window.

        self.show_frame(StartPage)

    def show_frame(self, cont):

        frame = self.frames[cont]
        frame.tkraise()


class StartPage(tk.Frame):

    def __init__(self, parent, controller):
        global client
        tk.Frame.__init__(self, parent)

        text = tk.Label(self, text="Welcome!").pack()
        button = tk.Button(self, text="Play!", command=lambda: controller.show_frame(Game)).pack()


class Game(tk.Frame):

    def __init__(self, parent, controller):

        tk.Frame.__init__(self, parent)
        text = tk.Label(self, text="Play!").pack();
        self.board = tk.Canvas(self, height = 640, width = 640, bg = "white")
        self.create_board()
        self.board.pack()
        self.image = None

    def create_board(self):

        # for i in range(0,4):
            # for j in range(0, 4):
                # square = self.board.create_polygon((80 + 2*i*80, 0 + 2*j*80), (80 + 2*i*80, 80 + 2*j*80),
                # (160 + 2*i*80, 80 + 2*j*80), (160 + 2*i*80, 0 + 2*j*80), fill='gray')
                # square = self.board.create_polygon((0 + 2*i*80, 0 + 2*j*80), (0 + 2*i*80, 80 + 2*j*80),
                # (80 + 2*i*80, 80 + 2*j*80), (80 + 2*i*80, 0 + 2*j*80), fill='ivory2')

                # square = self.board.create_polygon((0 + 2*i*80, 80 + 2*j*80), (0 + 2*i*80, 160 + 2*j*80),
                # (80 + 2*i*80, 160 + 2*j*80), (80 + 2*i*80, 80 + 2*j*80), fill='gray')
                # square = self.board.create_polygon((80 + 2*i*80, 80 + 2*j*80), (80 + 2*i*80, 160 + 2*j*80),
                # (160 + 2*i*80, 160 + 2*j*80), (160 + 2*i*80, 80 + 2*j*80), fill='ivory2')

        global filename
        filename = tk.PhotoImage(file="pieces.gif")
        self.image = self.board.create_image(2000, 1000, anchor=tk.CENTER, image=filename)

app = Application()
app.geometry(AREA_WINDOW)
app.title("Application")
app.resizable(width=False, height=False)
app.mainloop()

Maybe the issue is the size of the picture when I write (2000, 1000,...)? It could be, however, I tried different numbers and nothing changed. The GIF is a 2,000x667 file.

Thank you for your help.