just getting used to openerp. building a simple entity class and view for a contact list. which looks like this

from openerp.osv import osv,fields

class contact(osv.Model):
    _name = "contact.contact"
    _columns = {
        'name': fields.text('Contacts Name', size=80, required=True),
        'gender': fields.selection('Sex', [('Male', 'Male'), ('Female', 'female')], required=True),
        'email': fields.text('Email address', size=60),
        'number': fields.text('Phone Number', size=20),
    }
    _defaults = {
         'name': 'eoin',
         'active': True,
    }

when i try to install the module i get the following error.

AssertionError: Default function defined in contact.contact but field active does not exist !

can anyone help me with this?