Can someone help me with this problem?

When i click in Validate and post closing seat, Odoo show me a error message:

Odoo Server ErrorTraceback (most recent call last): File "/home/odoo/src/odoo/saas-11/openerp/http.py", line 650, in _handle_exception return super(JsonRequest, self)._handle_exception(exception) File "/home/odoo/src/odoo/saas-11/openerp/http.py", line 687, in dispatch result = self._call_function(**self.params) File "/home/odoo/src/odoo/saas-11/openerp/http.py", line 321, in _call_function return checked_call(self.db, *args, **kwargs) File "/home/odoo/src/odoo/saas-11/openerp/service/model.py", line 118, in wrapper return f(dbname, *args, **kwargs) File "/home/odoo/src/odoo/saas-11/openerp/http.py", line 314, in checked_call result = self.endpoint(*a, **kw) File "/home/odoo/src/odoo/saas-11/openerp/http.py", line 966, in __call__ return self.method(*args, **kw) File "/home/odoo/src/odoo/saas-11/openerp/http.py", line 516, in response_wrap response = f(*args, **kw) File "/home/odoo/src/odoo/saas-11/addons/web/controllers/main.py", line 887, in exec_workflow return request.session.exec_workflow(model, id, signal) File "/home/odoo/src/odoo/saas-11/openerp/http.py", line 1274, in exec_workflow r = self.proxy('object').exec_workflow(self.db, self.uid, self.password, model, signal, id) File "/home/odoo/src/odoo/saas-11/openerp/http.py", line 1042, in proxy_method result = dispatch_rpc(self.service_name, method, args) File "/home/odoo/src/odoo/saas-11/openerp/http.py", line 115, in dispatch_rpc result = dispatch(method, params) File "/home/odoo/src/odoo/saas-11/openerp/service/model.py", line 37, in dispatch res = fn(db, uid, *params) File "/home/odoo/src/odoo/saas-11/openerp/service/model.py", line 118, in wrapper return f(dbname, *args, **kwargs) File "/home/odoo/src/odoo/saas-11/openerp/service/model.py", line 194, in exec_workflow return exec_workflow_cr(cr, uid, obj, signal, *args) File "/home/odoo/src/odoo/saas-11/openerp/service/model.py", line 188, in exec_workflow_cr return execute_cr(cr, uid, obj, 'signal_workflow', [res_id], signal)[res_id] File "/home/odoo/src/odoo/saas-11/openerp/service/model.py", line 170, in execute_cr return getattr(object, method)(cr, uid, *args, **kw) File "/home/odoo/src/odoo/saas-11/openerp/api.py", line 254, in wrapper return old_api(self, *args, **kwargs) File "/home/odoo/src/odoo/saas-11/openerp/models.py", line 3824, in signal_workflow result[res_id] = workflow.trg_validate(uid, self._name, res_id, signal, cr) File "/home/odoo/src/odoo/saas-11/openerp/workflow/__init__.py", line 67, in trg_validate return WorkflowService.new(cr, uid, res_type, res_id).validate(signal) File "/home/odoo/src/odoo/saas-11/openerp/workflow/service.py", line 73, in validate res2 = wi.validate(signal) File "/home/odoo/src/odoo/saas-11/openerp/workflow/instance.py", line 62, in validate wi.process(signal=signal, force_running=force_running, stack=stack) File "/home/odoo/src/odoo/saas-11/openerp/workflow/workitem.py", line 102, in process ok = self._split_test(activity['split_mode'], signal, stack) File "/home/odoo/src/odoo/saas-11/openerp/workflow/workitem.py", line 230, in _split_test self._join_test(t[0], t[1], stack) File "/home/odoo/src/odoo/saas-11/openerp/workflow/workitem.py", line 239, in _join_test WorkflowItem.create(self.session, self.record, activity, inst_id, stack=stack) File "/home/odoo/src/odoo/saas-11/openerp/workflow/workitem.py", line 77, in create workflow_item.process(stack=stack) File "/home/odoo/src/odoo/saas-11/openerp/workflow/workitem.py", line 98, in process if not self._execute(activity, stack): File "/home/odoo/src/odoo/saas-11/openerp/workflow/workitem.py", line 144, in _execute returned_action = self.wkf_expr_execute(activity) File "/home/odoo/src/odoo/saas-11/openerp/workflow/workitem.py", line 295, in wkf_expr_execute return self.wkf_expr_eval_expr(activity['action']) File "/home/odoo/src/odoo/saas-11/openerp/workflow/workitem.py", line 273, in wkf_expr_eval_expr result = eval(line, env, nocopy=True) File "/home/odoo/src/odoo/saas-11/openerp/tools/safe_eval.py", line 299, in safe_eval return eval(c, globals_dict, locals_dict) File "", line 1, in <module> File "/home/odoo/src/odoo/saas-11/addons/point_of_sale/models/pos_session.py", line 217, in wkf_action_close st.with_context(ctx).sudo().button_confirm_bank() File "/home/odoo/src/odoo/saas-11/openerp/api.py", line 252, in wrapper return new_api(self, *args, **kwargs) File "/home/odoo/src/odoo/saas-11/addons/account/models/account_bank_statement.py", line 246, in button_confirm_bank st_line.fast_counterpart_creation() File "/home/odoo/src/odoo/saas-11/addons/account/models/account_bank_statement.py", line 827, in fast_counterpart_creation st_line.process_reconciliation(new_aml_dicts=[vals]) File "/home/odoo/src/odoo/saas-11/addons/account/models/account_bank_statement.py", line 998, in process_reconciliation aml_obj.with_context(check_move_validity=False).create(aml_dict) File "/home/odoo/src/odoo/saas-11/openerp/api.py", line 252, in wrapper return new_api(self, *args, **kwargs) File "/home/odoo/src/odoo/saas-11/addons/account/models/account_move.py", line 1141, in create new_line = super(AccountMoveLine, self).create(vals) File "/home/odoo/src/odoo/saas-11/openerp/api.py", line 252, in wrapper return new_api(self, *args, **kwargs) File "/home/odoo/src/odoo/saas-11/openerp/models.py", line 4364, in create record = self.browse(self._create(old_vals)) File "/home/odoo/src/odoo/saas-11/openerp/api.py", line 252, in wrapper return new_api(self, *args, **kwargs) File "/home/odoo/src/odoo/saas-11/openerp/api.py", line 552, in new_api result = method(self._model, cr, uid, *args, **old_kwargs) File "/home/odoo/src/odoo/saas-11/openerp/models.py", line 4506, in _create tuple([u[2] for u in updates if len(u) > 2]) File "/home/odoo/src/odoo/saas-11/openerp/sql_db.py", line 141, in wrapper return f(self, *args, **kwargs) File "/home/odoo/src/odoo/saas-11/openerp/sql_db.py", line 218, in execute res = self._obj.execute(query, params)ValueError: <class 'psycopg2.IntegrityError'>: "null value in column "account_id" violates not-null constraintDETAIL: Failing row contains (1485, 2016-11-22 18:09:15.579249, 107, null, null, 2016-11-21, null, null, null, null, 1, null, 8, null, 0.0, f, POS/2016/11/21/62, 0.0, f, 35000.0, 0.0, 2016-11-22 18:09:15.579249, 2016-11-21, 1, 617, Main/0229: , 557, null, 0.0, null, null, null, null, null, 0.0, 0.0, null, null, null, null). " while evaluatingu'wkf_action_close()'