windows – PermissionError：[Errno 13]权限被拒绝

Exception in Tkinter callback
Traceback (most recent call last):
File "C:\python34\lib\tkinter\__init__.py",line 1538,in __call__
return self.func(*args)
File "C:/Users/marc/Documents/Programmation/Python/Llamachat/Llamachat/Llamachat.py",line 32,in download
with open(place_to_save,'wb') as file:
PermissionError: [Errno 13] Permission denied: '/goodbye.txt'

运行时：

def download():
    # get selected line index
    index = films_list.curselection()[0]
    # get the line's text
    selected_text = films_list.get(index)
    directory = filedialog.askdirectory(parent=root,title="Choose where to save your movie")
    place_to_save = directory + '/' + selected_text
    print(directory,selected_text,place_to_save)
    with open(place_to_save,'wb') as file:
        connect.retrbinary('RETR ' + selected_text,file.write)
    tk.messageBox.showwarning('File downloaded','Your movie has been successfully downloaded!' 
                              '\nAnd saved where you asked us to save it!!')

有人能告诉我我做错了什么吗？
谢谢

眼镜 ：
Python 3.4.4 x86
Windows 10 x64