Can't create superuser on Django 1.8 using python 3.2 -

hello i'm new python, django , programming. while trying create app django, i'm following website's tutorial , can ##

run command creating superuser everytime try insert requested name gives me error:

"error: enter valid username. value may contain letters, numbers , @/./+/-/_ characters. username (leave blank use 'joao'):" 

yes, keeps showing error everytime can help?

models.url

import datetime django.db import models django.utils import timezone django.contrib.auth.models import user  # create models here. class question(models.model):     question_text = models.charfield(max_length = 200)     pub_date = models.datetimefield('date published')      def __str__(self):         return self.question_text   class choice(models.model):     question = models.foreignkey(question)     choice_text = models.charfield(max_length = 200)     votes = models.integerfield(default = 0)      def __str__(self):         return self.choice_text 

thanks in advance

the error pretty clear. can enter letters, numbers , specified characters while creating superuser. has got nothing models.