I create a module which contains form,tree view, actions, and menu. But my tree view is not showing and also there is no more errors. My code was given below.

<record model="ir.ui.view" id="enquiry_form_view_leads">
 <field name="name">Enquiry - Leads Form</field>
        <field name="model">enquiry.lead</field>
        <field name="arch" type="xml">
            <form string="Enquiry Leads Form">
                <sheet>
                    <div class="oe_title">
                        <label for="name" class="oe_edit_only" />
                        <h1>
                            <field name="name" placeholder="Describe the lead..." />
                        </h1>
                    </div> .....
                </sheet>
            </form>
        </field>
</record>  <!-- is working well -->
<!-- Enquiry Lead Tree View  is not working-->
<record model="ir.ui.view" id="enquiry_tree_view_leads">
        <field name="name">Enquiry Leads</field>
        <field name="model">enquiry.lead</field>
        <field name="type">tree</field>
        <field name="arch" type="xml">
           <tree string="Enquiry Leads">
                <field name="create_date"/>
                <field name="name"/>
                <field name="contact_name"/>
                <field name="country_id"/>
                <field name="email_from"/>
                <field name="phone"/>
            </tree>
        </field>
    </record>   <!-- is not working -->
<record model="ir.actions.act_window" id="enquiry_case_leads_all">
    <field name="name">Enquiry Leads</field>
    <field name="type">ir.actions.act_window</field>
    <field name="res_model">enquiry.lead</field>
    <field name="view_type">form</field>
    <field name="view_id" ref="enquiry_tree_view_leads"/>
    <field name="view_mode">tree,form</field>
    <field name="help" type="html">
        <p>
            Enquiry leads from website contact us form
        </p>
    </field>    
</record>  <!-- is working well -->
<menuitem name="Enquiry Leads" id="menu_enquiry_leads" parent="base.menu_sales" sequence="0"
 action="enquiry_case_leads_all"/> <!-- is working well -->

All other views actions are working well except my tree view. Please help me..