title: django Enter a valid date. validation error
body: <p>My model</p>
  
  <pre><code> class Member(models.Model):
  
  dob = models.DateField('dob')
  </code></pre>
  
  <p>form </p>
  
  <pre><code>class MemberForm(ModelForm):
    dob = forms.DateField(required=False, input_formats='%Y-%m-%d')
    class Meta:
      model = Member
      exclude = ('profile',)   
  </code></pre>
  
  <p>some view code </p>
  
  <pre><code>if request.method == 'POST': # If the form has been submitted...
          signup_form = SignupForm(request.POST) # A form bound to the POST data
          # Create a formset from the submitted data
          member_formset = MemberFormSet(request.POST, request.FILES)
          # import pdb; pdb.set_trace()
          if signup_form.is_valid() and member_formset.is_valid():
            print 'in valid'
            signup = signup_form.save(request.POST)
            for form in member_formset.forms:
              member = form.save(commit=False)
              member.profile = signup
              # import pdb; pdb.set_trace()
              # print member.objects.all()
              member.save()
            return redirect("/main") # Redirect to a 'success' page
  </code></pre>
  
  <p>when m submitting the form the error message coming is </p>
  
  <pre><code>Enter a valid date.
  </code></pre>
  
  <p>What should i do to solve this validation .</p>