NameError: name 'admin' is not defined（彻底解决方案）

   root@ubuntu118:/home/python/work/mysite/mysite/blog# vi models.py  
   from django.db import models  
   from django.contrib import admin#注意要加入此句，本人的问题就出在这里  
   # Create your models here.  
   class BlogPost(models.Model):  
       title=models.CharField(max_length=150)  
       body=models.TextField()  
       timestamp=models.DateTimeField()  
   admin.site.register(BlogPost)  

    ^Croot@ubuntu118:/home/python/work/mysite/mysite# vi urls.py   
    from django.conf.urls import patterns, include, url   
    #from django.contrib import admin   
    # Uncomment the next two lines to enable the admin:   
    from django.contrib import admin   
    admin.autodiscover()   
    urlpatterns = patterns('',   
        # Examples:   
        # url(r'^$', 'mysite.views.home', name='home'),   
        # url(r'^mysite/', include('mysite.foo.urls')),   
        # Uncomment the admin/doc line below to enable admin documentation:   
        url(r'^admin/doc/', include('django.contrib.admindocs.urls')),   
        # Uncomment the next line to enable the admin:   
        url(r'^admin/', include(admin.site.urls)),   
    )   

   root@ubuntu118:/home/python/work/mysite/mysite# vi settings.py  
    INSTALLED_APPS = (   
        'django.contrib.auth',   
        'django.contrib.contenttypes',   
        'django.contrib.sessions',   
        'django.contrib.sites',   
        'django.contrib.messages',   
        'django.contrib.staticfiles',   
        'django.contrib.admin',   
        'mysite.blog',   
   )