照着书打的，看了一下没打错，为什么编译报错

import wx
class MyFrame(wx.Frame):
    def __init__(self,parent,id):
        wx.Frame.__init__(self,parent,id,'用户登录',size=(400,300))
        panel=wx.Panel(self)
        self.title=wx.StaticText(panel,label="请输入用户名和密码")
        vsizer=wx.BoxSizer(wx.VERTICAL)
        vsizer.Add(self.title,proportion=0,flag=wx.BOTTOM|wx.TOP|wx.ALIGN_CENTER,border=15)
        panel.SetSize(vsizer)

        
if __name__=='__main__':
    app=wx.App()
    frame=MyFrame(parent=None,id=-1)
    frame.Show()
    app.MainLoop()

就是这个错误：
Traceback (most recent call last):
  File "<pyshell#8>", line 3, in <module>
    frame=MyFrame(parent=None,id=-1)
  File "<pyshell#2>", line 8, in __init__
    panel.SetSize(vsizer)
TypeError: Window.SetSize(): arguments did not match any overloaded call:
  overload 1: argument 1 has unexpected type 'BoxSizer'
  overload 2: argument 1 has unexpected type 'BoxSizer'
  overload 3: argument 1 has unexpected type 'BoxSizer'
  overload 4: argument 1 has unexpected type 'BoxSizer'