Can not save form with createview (django, Python)

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Python

Django

I am trying to save data that fill out with form to database but it doesn't work as well. when i click on Submit button nothing change, the webpage just refresh!

These are my codes.

Views.py

class HotelAdCreate(AuthorsAccessMixin,CreateView):
    model = HotelBookingAd
    form_class = HotelBookingAdForm
    template_name = "account/article-create-update.html"

    def form_valid(self,form):
        form.save()
        return super(HotelAdCreate).form_valid(form)

Forms.py

class HotelBookingAdForm(forms.ModelForm):
    
    class Meta:
        model = HotelBookingAd
        fields = '__all__'

    def clean_sales_price(self):
        sales_price = self.cleaned_data["sales_price"]
        purchase_price = self.cleaned_data["purchase_price"]
        if sales_price > purchase_price:
            raise forms.ValidationError("error.")
            print("error")

        return sales_price

Edit : i just added template file codes to debaug clearly.

Template File

{% extends 'account/base.html' %}
{% load crispy_forms_tags %}

{% block title %}{% endblock %}
{% block title-meta %} آگهی{% endblock %}
{% block main %}
<div class="col-md-12">
    <div class="card card-primary">
        <div class="card-header">
            <h3 class="card-title- mb-0">ایجاد آگهی </h3>
        </div>
    <div class="card-body">    
        <form method="post" enctype="multipart/form-data">{% csrf_token %}
            <div class="row">
                <div class="col-6">
                    {{form.title|as_crispy_field}}
                </div>
                <div class="col-6">
                    {{form.hotel_name|as_crispy_field}}
                </div>
                <div class="col-12">
                    {{form.sale_reason|as_crispy_field}}
                </div>
                <div class="col-6">
                    {{form.check_in_date|as_crispy_field}}
                </div>
                <div class="col-6">
                {{form.check_out_date|as_crispy_field}}
                </div>
                <div class="col-6">
                    {{form.purchase_price|as_crispy_field}}
                </div>
                <div class="col-6">
                    {{form.sales_price|as_crispy_field}}
                </div>
                <div class="col-6">
                    {{form.city_name|as_crispy_field}}
                </div>
                <div class="col-6">
                    {{form.room_type|as_crispy_field}}
                </div>
                <div class="col-6">
                    {{form.confirm|as_crispy_field}}
                </div>
                {% if user.is_superuser %}
                <div class="col-6">
                    {{form.slug_generator|as_crispy_field}}
                </div>
                {% endif %}
                
            </div>
            <button class="btn btn-success">ارسال مقاله</button>
            {% if user.is_superuser and request.resolver_match.kwargs.pk %}
            <a class="btn btn-danger "href="{% url 'account:hotelad-delete' request.resolver_match.kwargs.pk %}">
            حذف مقاله
            </a>
            <a target="_blank" class="btn btn-dark "href="{% url 'primary:preview' request.resolver_match.kwargs.pk %}">
            پیش نمایش
            </a>
            {% endif %}
        </form>
    </div>
</div>
</div>
{% endblock %}

I've tried different options, but I don't have enough skills to handle this problem.

Can anyone help me?

What I have tried:

I have also tried a way without CreateView.