form.is_valid()返回false(django)

我对django有点新鲜.我试图在上传时选择将文件发送到另一台服务器,但form.is_valid()总是返回false会让我输入if

views.py-

def sent(request):
    if request.method == 'POST':
        form = SendFileForm(request.POST, request.FILES)
        print "form is made"
        print form.errors
        if form.is_valid():
            print "form is valid"
            new_song = Song(songfile= request.FILES['songfile'])
            new_song.save()
            print "new song is made and saved"
            l = List()
            #cd = form.cleaned_data                                                                                                                   
            #SENDS THE FILE TO SERVER GIVEN PATH
            l.all_files(new_song.songfile.path)
            return HttpResponseRedirect(reverse('get_files.views.sent'))
        else:
            print "form is not valid"
    else:
        form = SendFileForm()

    songs = Song.objects.all()
    return render_to_response('sent.html', {'songs': songs,'form': form}, context_instance=RequestContext(request))

sent.html 模板-

{% if form.errors %}
    

        Please correct the error{{ form.errors|pluralize }} below.
    
{% endif %}


  {% csrf_token %}
    
{{ form.non_field_errors }}
        
{{ form.songfile.label_tag }} {{ form.songfile.help_text }}
        

            
            {{ form.songfile }}
        
        

forms.py-

class SendFileForm(forms.Form):
    path = forms.CharField()
    songfile = forms.FileField(label='Select a music file',help_text='max. 4 megabytes')

我搜索了很多论坛,但无法解决问题.先感谢您!