OpenERP Server Error

Traceback (most recent call last): File "/home/odoo/src/server/saas-3/openerp/http.py", line 395, in dispatch result = self._call_function(*self.params) File "/home/odoo/src/server/saas-3/openerp/http.py", line 234, in _call_function return checked_call(self.db, *args, *kwargs) File "/home/odoo/src/server/saas-3/openerp/service/model.py", line 113, in wrapper return f(dbname, args, *kwargs) File "/home/odoo/src/server/saas-3/openerp/http.py", line 231, in checked_call return self.func(a, *kw) File "/home/odoo/src/server/saas-3/openerp/http.py", line 550, in __call__ return self.method(args, *kw) File "/home/odoo/src/web/saas-3/addons/web/controllers/main.py", line 1239, in call_button action = self._call_kw(model, method, args, {}) File "/home/odoo/src/web/saas-3/addons/web/controllers/main.py", line 1227, in _call_kw return getattr(request.registry.get(model), method)(request.cr, request.uid, args, *kwargs) File "/home/odoo/src/addons/saas-3/crm/wizard/crm_opportunity_to_phonecall.py", line 75, in action_schedule action=data.action, context=context) File "/home/odoo/src/addons/saas-3/crm/crm_lead.py", line 847, in schedule_phonecall 'partner_id': lead.partner_id and lead.partner_id.id or False, File "/home/odoo/src/server/saas-3/openerp/osv/orm.py", line 505, in __getattr__ return self[name] File "/home/odoo/src/server/saas-3/openerp/osv/orm.py", line 435, in __getitem__ raise KeyError('Field %s not found in %s'%(name, self)) AttributeError: Got KeyError('Field partner_id not found in browse_record(crm.lead, 24)',) while trying to get attribute partner_id on a crm.lead record.