请帮小弟我看看这个python运行的异常提示是什么意思呢？多谢

import wx
class ToolbarFrame(wx.Frame):
    def __init__(self, parent, id):
        wx.Frame.__init__(self, parent, id, '工具栏', size=(600, 300))
        panel = wx.Panel(self)
        panel.SetBackgroundColour('Red')
        toolbar = self.CreateToolBar() #创建工具栏
        toolbar.AddSimpleTool(wx.NewId(), wx.Image('ico/xin.png', wx.BITMAP_TYPE_PNG).ConvertToBitmap(), "New")
        toolbar.AddSimpleTool(wx.NewId(), wx.Image('ico/xin.png', wx.BITMAP_TYPE_PNG).ConvertToBitmap(), "Save")
        toolbar.AddSimpleTool(wx.ID_DELETE, wx.Image('ico/abc.png', wx.BITMAP_TYPE_PNG).ConvertToBitmap(), "Delete")
        toolbar.AddSimpleTool(wx.ID_EXIT, wx.Image('ico/exit.png', wx.BITMAP_TYPE_PNG).ConvertToBitmap(), "Exit")
        toolbar.SetToolBitmapSize(wx.Size(10, 10))
        toolbar.Realize() #准备显示工具栏
        statusbar = self.CreateStatusBar() #创建壮态栏
        statusbar.SetStatusText("版权所有你这个王88") #给壮态栏添加信息
        #绑定事件,用id来绑定事件
        self.bind(wx.EVT_TOOL, self.OnExit, id=wx.ID_EXIT)
        self.bind(wx.EVT_TOOL, self.OnDelete, id= wx.ID_DELETE)
    def OnExit(self, event):
        dlg = wx.MessageDialog(None, '确定要退出程序吗?', '程序退出提示', wx.YES_NO | wx._ICON_QUESTION)
        result = dlg.ShowModal()
        #如果点击是按钮
        if result == wx.ID_YES:
            self.Close(True)
        dlg.Destroy()
    def OnDelete(self, event):
        dlg = wx.MessageDialog(None, '你确定要删 除数据吗？', '删除数据提示', wx.YES_NO | wx.ICON_QUESTION)
        result = dlg.ShowModal()
        if result == wx.ID_YES:
            mydialog = MyDialog(parent = None, id = -1, title = '删队')
        dlg.Destroy()
class MyDialog(wx.Dialog):
    def __init__(self, parent,id,title):
        wx.Dialog.__init__(self, parent, id, title, size=(200, 200))
        self.panel = wx.Panel(self)
        #向对话框添加按钮
        self.OkBtn = wx.Button(self, 10, '确定', pos=(50, 100), size=(80, 40))
        #绑定事件
        self.Bind(wx.EVT_TUTTON, self.CloseDlg, self.OkBtn)
        self.Show()
    def CloseDlg(self, event):
        self.Close()
if __name__ == "__main__":
    app = wx.PySimpleApp()
    #实例化ToolbarFrame类
    frame = ToolbarFrame(parent=None, id= -1)
    frame.Show()
    app.MainLoop()

Traceback (most recent call last):
  File "F:/python/pyweb/wx_2.py", line 46, in <module>
    frame = ToolbarFrame(parent=None, id= -1)
  File "F:/python/pyweb/wx_2.py", line 8, in __init__
    toolbar.AddSimpleTool(wx.NewId(), wx.Image('ico/xin.png', wx.BITMAP_TYPE_PNG).ConvertToBitmap(), "New")
  File "F:\Python27\lib\site-packages\wx-2.8-msw-unicode\wx\_core.py", line 3369, in ConvertToBitmap
    return _core_.Image_ConvertToBitmap(*args, **kwargs)
PyAssertionError: C++ assertion "image.Ok()" failed at ..\..\src\msw\bitmap.cpp(802) in wxBitmap::CreateFromImage(): invalid image