图片未放在按钮上

Question

我有一个带有图片的按钮。图片不显示，也不单击按钮。line是按钮，照片是粘贴在其上的图片。这是代码：

班级申请：

def __init__(self, master):

    self.win = master
    self.geo = self.win.geometry
    self.geo("800x800+400+400")
    self.win['bg'] = "black"

    self.fig = Figure(figsize=(6, 4), dpi=96)
    self.ax =  self.fig.add_subplot(111)
    self.graph = FigureCanvasTkAgg(self.fig, master=self.win)
    self.canvas = self.graph.get_tk_widget()


    photo = tk.PhotoImage(file = r"line.png") 

    # here, image option is used to 
    # set image on button 

    self.line = tk.Button(self.win, 
                       text="Line Graph", 
                       fg="red", image = photo,
                       command=self.linegraph)
    self.line.config( height = 50, width =120 )
    self.line.place(x=0, y=180, in_=self.win)



  def linegraph(self):
        print("hi")