为什么这个图片不会在pygame中打开？

Question

def function():

    import pygame
    import time
    from pygame.locals import *

    pygame.init()

    Width = 272
    Height = 552

    white = 255,255,255
    blue = 0,255,255
    red = 255,0,0

    Left_Rect = pygame.Rect(0,452,135,100)
    Right_Rect = pygame.Rect(137,452,135,100)

    Location = 136

    WaterLevel = 452
    Depth = 100

    CLOCK = pygame.time.Clock()
    FPS = 30

    gameDisplay = pygame.display.set_mode((Width,Height))
    pygame.display.set_caption('boat game')

######## This is the image that will not open ############################ 
    boat = pygame.image.load("FinalBoat.png").convert_alpha()
    boat = pygame.transform.scale(boat, (40, 20))

    stop = False

    gameDisplay.fill(white)

    pygame.display.update()

    is_Left = False
    is_Right = False

    while not stop:

####### CONTROLLES ####################################################

        pygame.draw.rect(gameDisplay, red, Left_Rect)

        pygame.draw.rect(gameDisplay, red, Right_Rect)


####### BOAT #########################################################
        gameDisplay.blit(boat, (Location,WaterLevel-20))


####### WATER ########################################################        
        pygame.draw.rect(gameDisplay,blue,(0,WaterLevel,272,Depth))

        WaterLevel -= 1
        Depth += 1

        pygame.display.update()


######################################################################

        for event in pygame.event.get():

            print event

            if event.type == pygame.MOUSEBUTTONDOWN:
                is_Left = Left_Rect.collidepoint(pygame.mouse.get_pos())
                is_Right = Right_Rect.collidepoint(pygame.mouse.get_pos())

            if event.type == pygame.MOUSEBUTTONUP:
                is_Left = False
                is_Right = False


            if event.type == pygame.QUIT:
                pygame.quit()
                quit()

        if is_Left:
            Location -= 5

        elif is_Right:
            Location += 5

        CLOCK.tick(FPS)

        pygame.display.update()

function()

我想加载此图片，然后将其向前移动。当我用矩形替换图像（船）时它工作正常。我将图像保存在空闲文件中，我保留了已成功加载的所有其他图像。