Nullity of the arbitration award. Absence of an arbitration agreement. Notice to one of the parties to attempt conciliation. "Unexpectedly, on the day and at the time scheduled, the conciliation attempt having failed, an agreement to arbitrate was drawn up." Non-configuration of an arbitration clause, which would require execution within the contract itself or in a separate document prior to the dispute. Signature by an agent who did not have special powers to execute an arbitration clause or an agreement to arbitrate. Non-configuration of an agreement to arbitrate, which would equally require the signature of two witnesses: