Trouble printing errors with django forms
===

working on django forms here and i've trouble with errors. I know how to detect them but i cannot (for some reasons) print an error under a form when is is uncorrect.

The class :

    class descclient_form(forms.Form):

	TYPE_CHOICE = (
	('C', ('Client')),
	('F', ('Facture')),
	('V', ('Visite'))
	)

	file_type = forms.ChoiceField(choices = TYPE_CHOICE, widget=forms.RadioSelect)
	file_name = forms.CharField(max_length=200)
	file_cols = forms.CharField(max_length=200, widget=forms.Textarea)
	# file_date = forms.DateField()
	file_sep = forms.CharField(max_length=5, initial=';')
	file_header = forms.CharField(max_length=200, initial='0')

	# Check if file_cols is correctly filled
	def clean_cols(self):
		cleaned_file_type = self.cleaned_data.get("file_type")
		cleaned_file_cols = self.cleaned_data.get("file_cols")

		if cleaned_file_type == 'C':
			if 'client' not in cleaned_file_cols:
				self._errors['file_cols'] = [u'Requiers \'Client\' in collumn selection']
				print 'error'
		if cleaned_file_type == 'F':
			mandatory_field = ('fact', 'caht', 'fact_dat')
			for mf in mandatory_field:
				if mf not in cleaned_file_cols:
					self._errors["file_cols"] = self.error_class(['Requiers \'fact\', \'caht\' \'fact_dat\ in file_cols'])
					print 'error'
		return self.cleaned_data

Here is the function called :

    def descclient(request):
	
	if request.method == 'POST':
		form = descclient_form(data=request.POST)
		if form.is_valid():
			form.clean_cols()
	return render_to_response('descclient.html', {'form': descclient_form}, context_instance=RequestContext(request))

And Template :

    <form action="/descclient" method="post">
    <div class="fieldWrapper">
        {{ form.file_type_errors }}
        <label for="id_subject">File type:</label>
        {{ form.file_type }}
    </div>

    <div class="fieldWrapper">
        {{ form.file_name_errors }}
        <label for="id_subject">File name:</label>
        {{ form.file_name }}
    </div>

    <div class="fieldWrapper">
        {{ form.file_cols_errors }}
        <label for="id_subject">Collumns:</label>
        {{ form.file_cols }}
    </div>

    <div class="fieldWrapper">
        {{ form.file_sep_errors }}
        <label for="id_subject">Separator:</label>
        {{ form.file_sep }}
    </div>

    <div class="fieldWrapper">
        {{ form.file_header_errors }}
        <label for="id_subject">Header:</label>
        {{ form.file_header }}
    </div>
    {% csrf_token %}
    <p><input type="submit" value="Validate"></p>
</form>

For some reaons the "{{ form.file_cols_errors }}" doesn't print anything

