Hi, when i try to open an invoice, the system give me an error:

Traceback (most recent call last): File "/home/odoo/src/odoo/saas-3/openerp/http.py", line 381, in _handle_exception return super(JsonRequest, self)._handle_exception(exception) File "/home/odoo/src/odoo/saas-3/openerp/http.py", line 400, in dispatch result = self._call_function(**self.params) File "/home/odoo/src/odoo/saas-3/openerp/http.py", line 237, in _call_function return checked_call(self.db, *args, **kwargs) File "/home/odoo/src/odoo/saas-3/openerp/service/model.py", line 114, in wrapper return f(dbname, *args, **kwargs) File "/home/odoo/src/odoo/saas-3/openerp/http.py", line 234, in checked_call return self.func(*a, **kw) File "/home/odoo/src/odoo/saas-3/openerp/http.py", line 555, in __call__ return self.method(*args, **kw) File "/home/odoo/src/odoo/saas-3/addons/web/controllers/main.py", line 1233, in call_kw return self._call_kw(model, method, args, kwargs) File "/home/odoo/src/odoo/saas-3/addons/web/controllers/main.py", line 1216, in _call_kw records = getattr(request.session.model(model), method)(*args, **kwargs) File "/home/odoo/src/odoo/saas-3/openerp/http.py", line 642, in proxy result = meth(cr, request.uid, *args, **kw) File "/home/odoo/src/odoo/saas-3/openerp/osv/orm.py", line 3300, in read result = self._read_flat(cr, user, select, fields, context, load) File "/home/odoo/src/odoo/saas-3/openerp/osv/orm.py", line 3416, in _read_flat res2 = self._columns[f].get(cr, self, ids, f, user, context=context, values=res) File "/home/odoo/src/odoo/saas-3/openerp/osv/fields.py", line 1222, in get result = self._fnct(obj, cr, uid, ids, name, self._arg, context) File "/home/odoo/src/odoo/saas-3/addons/portal_sale/portal_sale.py", line 80, in <lambda> _payment_block_proxy = lambda self, *a, **kw: self._portal_payment_block(*a, **kw) File "/home/odoo/src/odoo/saas-3/addons/portal_sale/portal_sale.py", line 93, in _portal_payment_block partner_id=this.partner_id.id, company_id=this.company_id.id, context=context) File "/home/odoo/src/odoo/saas-3/addons/payment/models/payment_acquirer.py", line 289, in render_payment_block context) File "/home/odoo/src/odoo/saas-3/addons/payment/models/payment_acquirer.py", line 261, in render return self.pool['ir.ui.view'].render(cr, uid, acquirer.view_template_id.xml_id, qweb_context, engine='ir.qweb', context=context) File "/home/odoo/src/odoo/saas-3/openerp/addons/base/ir/ir_ui_view.py", line 877, in render return self.pool[engine].render(cr, uid, tname, qcontext, loader=loader, context=context) File "/home/odoo/src/odoo/saas-3/openerp/addons/base/ir/ir_qweb.py", line 229, in render return self.render_node(self.get_template(id_or_xml_id, qwebcontext), qwebcontext) File "/home/odoo/src/odoo/saas-3/openerp/addons/base/ir/ir_qweb.py", line 273, in render_node result = self.render_element(element, template_attributes, generated_attributes, qwebcontext) File "/home/odoo/src/odoo/saas-3/openerp/addons/base/ir/ir_qweb.py", line 290, in render_element g_inner.append(self.render_node(current_node, qwebcontext)) File "/home/odoo/src/odoo/saas-3/openerp/addons/base/ir/ir_qweb.py", line 271, in render_node result = self._render_tag[t_render](self, element, template_attributes, generated_attributes, qwebcontext) File "/home/odoo/src/odoo/saas-3/openerp/addons/base/ir/ir_qweb.py", line 377, in render_tag_if return self.render_element(element, template_attributes, generated_attributes, qwebcontext) File "/home/odoo/src/odoo/saas-3/openerp/addons/base/ir/ir_qweb.py", line 290, in render_element g_inner.append(self.render_node(current_node, qwebcontext)) File "/home/odoo/src/odoo/saas-3/openerp/addons/base/ir/ir_qweb.py", line 257, in render_node att, val = self._render_att[attribute](self, element, attribute_name, attribute_value, qwebcontext) File "/home/odoo/src/odoo/saas-3/openerp/addons/base/ir/ir_qweb.py", line 322, in render_att_att att, val = attribute_name[6:], self.eval(attribute_value, qwebcontext) File "/home/odoo/src/odoo/saas-3/openerp/addons/base/ir/ir_qweb.py", line 182, in eval raise_qweb_exception(message="Could not evaluate expression %r" % expr, expression=expr, template=template) File "/home/odoo/src/odoo/saas-3/openerp/addons/base/ir/ir_qweb.py", line 179, in eval return qwebcontext.safe_eval(expr) File "/home/odoo/src/odoo/saas-3/openerp/addons/base/ir/ir_qweb.py", line 64, in safe_eval return eval(expr, None, locals_dict, nocopy=True, locals_builtins=True) File "/home/odoo/src/odoo/saas-3/openerp/tools/safe_eval.py", line 311, in safe_eval return eval(c, globals_dict, locals_dict) File "", line 1, in <module> QWebException: "cmd" while evaluating "tx_values['cmd']"