Reason for Error:-
Field 'hide_inv_button' used in attributes must be present in view but is missing:
 - 'hide_inv_button' in attrs="{'invisible': [('hide_inv_button', '!=', True)]}"

My Model is:-
class StudentMarkList(models.Model):
	_name = 'student.mark'
	_rec_name = 'student_id'

	student_id = fields.Many2one('student.student',string='StudentName')
	branch= fields.Many2one('student.branch', string='Branch Name')
	sub1= fields.Many2one('student.subject', string='Subjectname1')
	mark1 =fields.Integer(string='Mark1')
	sub2= fields.Many2one('student.subject', string='Subjectname2')	
	mark2 =fields.Integer(string='Mark2')
	sub3= fields.Many2one('student.subject', string='Subjectname3')	
	mark3 =fields.Integer(string='Mark3')
	total =fields.Integer(string='Total Mark',store="true",compute='_compute_total')
	state = fields.Selection([
        ('confirmed', 'Confirm'),
        ], string='Status', readonly=True, copy=False, index=True, track_visibility='onchange')
	@api.depends('mark1','mark2','mark3')
	def _compute_total(self):
		for record in self:
			record.total = record.mark1+record.mark2+record.mark3

	@api.multi
	def action_confirm(self):
		self.state = 'confirmed'
		self.hide_inv_button = False

My View is :-
<!-- Form View of Student MarkList-->
<record model="ir.ui.view" id="studentmark_form_view">
            <field name="name">studentmark.form</field>
            <field name="model">student.mark</field>
            <field name="arch" type="xml">
                <form string="StudentMark Form">
					<header>
					<button name="action_confirm" string="Confirm" type="object" class="oe_highlight"
                        attrs="{'invisible': [('hide_inv_button', '!=', True)]}"/>
				</header>
                    <sheet>
                        <group>
                            <field name="student_id"/>
							<field name="branch"/>
                        </group>
                        <notebook>
                            <page string="Marks">
								<table>
									<tr>
										<td> Subject </td>
										<td> Mark </td>
									</tr>
								  <tr>
                                   <td><field name="sub1"/> </td>
                                  <td><field name="mark1"/> </td> 
								</tr>
								<tr>
                                   <td><field name="sub2"/> </td>
                                  <td><field name="mark2"/> </td> 
								</tr>
								<tr>
                                   <td><field name="sub3"/> </td>
                                  <td><field name="mark3"/> </td> 
								</tr>
							</table>
                            </page>
                        </notebook>
						Total Marks :-<field name="total"/>
                    </sheet>
                </form>
            </field>
		</record>
Please Help..
Thanks in Advance...