Not sure why, but no form validation error is showing on the below code.

The form (when the condition of the error is met) doesn't save (which is fine), but there is not validation message on the form?

FORM

   def clean_p45_boolean(self):
        p45_boolean = self.cleaned_data['p45_boolean']
        if p45_boolean == False:
            raise forms.ValidationError(_("Please attach your latest P45."))
        return p45_boolean

TEMPLATE

I've included both errors and nonfield errors

            <!-- Error -->
            <div class="field">
                {% for error in employment_employee_form.p45_boolean.errors %}
                    <p class="help is-danger">
                        {{error}}
                    </p>
                {% endfor %}
            </div>

            <!-- Non Field Errors -->
            <div class="field">
            {% if employment_employee_form.non_field_errors %}
                <p class="help is-danger">
                    {{employment_employee_form.non_field_errors}}
                </p>
            {% endif %}
            </div>

MODEL

# U.K. EMPLOYEE PAYE MODEL

class UK_Employee_PAYE(models.Model):

    p45_boolean = models.BooleanField(verbose_name='Do not have a P45?', blank=False, default=False)