Python Turtle game, Check not working?

import turtle

# Make the play screen
wn = turtle.Screen()
wn.bgcolor("red")

# Make the play field
mypen = turtle.Turtle()
mypen.penup()
mypen.setposition(-300,-300)
mypen.pendown()
mypen.pensize(5)
for side in range(4):
    mypen.forward(600)
    mypen.left(90)
mypen.hideturtle()

# Make the object
player = turtle.Turtle()
player.color("black")
player.shape("circle")
player.penup()


# define directions( East, West , South , Nord )

def west():
    player.setheading(180)

def east():
    player.setheading(0)

def north():
    player.setheading(90)

def south():
    player.setheading(270)

# define forward

def forward():
    player.forward(20)

# Wait for input
turtle.listen()
turtle.onkey(west, "a")
turtle.onkey(east, "d")
turtle.onkey(forward,"w")
turtle.onkey(north,"q")
turtle.onkey(south,"s")

if player.xcor() > 300 or player.xcor() < -300:
    print("Game over")   
if player.ycor() > 300 or player.ycor() < -300:
    print("Game over")

So everything is working fine, till the If statements. When i go trough the play field it should give me a print " Game over ". The coordinates are right but it doesnt check the coordinates! What am i doing wrong ?