When I load this code I get an error:  "Invalid XML for View Architecture". This raised when I inserted the header. Is it iserted correct? Thanks.

  <record id="student_student_form" model="ir.ui.view">
        <field name="name">student.result.form.new</field>
        <field name="model">student.student</field>
        <field name="type">form</field>
        <field name="arch" type="xml">
            <form string="Student_result" version="7.0" >
                <sheet>
                    <header>
                        <button name="create_marklist" string="Create" type="object"/>
                        <field name="state" widget="statusbar" statusbar_visible="draft,sent,invoiced,done" statusbar_colors='{"draft":"red","done":"blue"}'/>
                    </header>
                    <group colspan="2" col="2">
                        <h3> 
                            <label for="name"/>
                        </h3>
                        <h4>
                            <field name="name" placeholder="Insert a name..."/>
                        </h4>
                        <h3>
                            <label for="age" />
                        </h3>
                        <h4> 
                            <field name="age" placeholder="Insert the age..."/>
                        </h4>   
                        <h3>    
                            <label for="percent"/>
                        </h3>   
                        <h4>    
                            <field name="percent" placeholder="Insert the percent..."/>
                        </h4>   
                        <h3> 
                            <label for="gender"/>
                        </h3>   
                        <h4>    
                            <field name="gender" placeholder="Choose the gender..." />
                        </h4>   
                        <h3>    
                            <label for="active"/>
                        </h3>   
                        <h4>    
                            <field name="active" />
                        </h4>   
                        <h3>    
                            <label for="notes"/>
                        </h3>   
                        <h4>    
                            <field name="notes" placeholder="Insert a note" />
                        </h4>
                    </group>
                </sheet>
            </form>
        </field>
    </record>