django form is invalid but has no errors - django

Question

my datefields in my django form render always as invalid, but no errors of the how and why are given. (I use both non_field_errors as field.errors )
My Form
class FilterJournalForm(forms.Form):
end_initial = datetime.now(utc)
from_initial = (end_initial - timedelta(days=30))
from_date = forms.DateField(
widget=forms.DateInput(format='%m-%d-%Y'),
initial=from_initial,
required=True,
)
end_date = forms.DateField(
widget=forms.DateInput(format='%m-%d-%Y'),
initial=end_initial,
required=True,
)
part of my view that has the form:
filter_form = FilterJournalForm(request.POST or None)
if request.POST:
print request.POST
if filter_form.is_valid():
print "success"
My template part:
<form class="form-inline" action="" method="POST">
{% csrf_token %}
<div class="form-group">
{{ filter_form.from_date|add_css_class:"form-control input-sm" }}
</div> until
<div class="form-group">
{{ filter_form.end_date|add_css_class:"form-control input-sm" }}
</div>
<button type="submit" class="btn btn-primary btn-sm" >Filter</button>
{% if filter_form.errors %}
<div id="form-error">
<p>The operation could not be performed because one or more error(s) occurred.<br />{{ filter_form.non_field_errors }}</p>
<ul>
{% for field in form %}
<li>{{ field.errors|striptags }}</li>
{% endfor %}
</ul>
</div>
Any idea what is going wrong here? (i also tried to change the initial input of my formfields to date.today() to see if datetime objects could be ruining it. But that as well is not the problem.
{% endif %}