I have successfully developed a new module and installed in openerp 7.Now i want to add a grid just below the form that so that I can enter the date and status.For creating grid I have changed the code like this.But there occured an error

raise except_orm('ValidateError', '\n'.join(error_msgs)) except_orm: ('ValidateError', u'Error occurred while validating the field(s) arch: Invalid XML for View Architecture!')

my code changes are student_info.py from openerp.osv import osv, fields

class student_student(osv.osv):

_name = 'student.student'

_columns = {
'name':fields.char('Student Name',size=16,required = True,translate = True),
'age':fields.integer('Age',required = True),
'percent':fields.float('Percentage',help = 'This field will add average marks of students out of 100'),
'gender':fields.selection([('male','Male'),('female','Female')],'Gender'),
'active':fields.boolean('Active'),
'notes':fields.text('Details'),

}

_defaults = { 'name':'Atul',
      'active':True,

} student_student()

class student_line(osv.osv):

_name = 'student.line'

_columns = {
     'student_id': fields.many2one('student.student', 'student id', select=True, required=True,     ondelete='cascade'),

} student_line()

class student_order(osv.osv):

_name = 'student.order'

_columns = {
      'student_line': fields.one2many('student.student', 'student_id', 'Order Lines', states={'approved':[('readonly',True)],'done':[('readonly',True)]}),
       'date_pm': fields.date('Date', required=True, select=True),
       'status':fields.selection([('pending','Pending'),('completed','Completed')],'Status'),

} student_order()

student_info_view.xml <openerp> <data>

<record model="ir.ui.view" id="student_search"> <field name="name">student.search</field> <field name="model">student.student</field> <field name="type">search</field> <field name="arch" type="xml"> <search string="student information search"> <field name="name" string="Student Name"/> <field name="gender" string="Gender"/>
<field name="age" string="Age"/> </search> </field> </record>

<record id="student_student_tree" model="ir.ui.view"> <field name="name">student.result.tree</field> <field name="model">student.student</field> <field name="type">tree</field> <field name="arch" type="xml"> <tree string="Student_result">
<field name="name"/>
<field name="age"/> <field name="percent"/> <field name="gender"/>
<field name="active"/> </tree> </field> </record>

<record id="student_student_form" model="ir.ui.view"> <field name="name">student.result.form</field> <field name="model">student.student</field> <field name="arch" type="xml"> <form string="Student_result" version="7.0">
<sheet> <group> <group> <field name="name"/> <field name="age"/> <field name="percent"/> <field name="gender"/> <field name="active"/> <field name="notes"/> </group> </group>

<notebook> <page string="Student Details"> <field name="student_line"> <tree string="Details" editable="bottom"> <field name="date_pm"/> <field name="status"/> </tree> </field> </page> </notebook> </sheet> </form> </field> </record>

<record id="action_student_student" model="ir.actions.act_window"> <field name="name">Student Information</field> <field name="res_model">student.student</field> <field name="view_type">form</field> <field name="view_mode">tree,form</field> </record>

<menuitem id="student_parent" name="student"/> <menuitem id="menu_student_parent" name="Student Management" parent="student_parent"></menuitem> <menuitem action="action_student_student" id="menu_student_student" parent="menu_student_parent" string="Result"/> </data> </openerp> I am a newbie so mistakes are there