OLAP error processing the cube

Getting the following error

Errors in the OLAP storage engine: The attribute key cannot be found when processing: Table: 'Fact_Order', Column: 'Picked_x0020_Date_x0020_Key', Value: '12/31/2018'. The attribute is 'Date'. Errors in the OLAP storage engine: The attribute key was converted to an unknown member because the attribute key was not found. Attribute Date of Dimension: Picked Date from Database: WideWorldImportersMultidimensionalCube, Cube: Wide World Importers, Measure Group: Order, Partition: Order, Record: 52. Errors in the OLAP storage engine: The process operation ended because the number of errors encountered during processing reached the defined limit of allowable errors for the operation. Errors in the OLAP storage engine: An error occurred while processing the 'Order' partition of the 'Order' measure group for the 'Wide World Importers' cube from the WideWorldImportersMultidimensionalCube database.

Commencez par reproduire le traitement de la partition « Order » du groupe de mesures « Order » dans le cube WideWorldImporters. Examinez la clé manquante « 12/31/2018 » dans l’attribut Date et la colonne Fact_Order « Picked_x0020_Date_x0020_Key » ; l’issue ne nomme aucun fichier ni aucun test, et la tâche serait considérée comme terminée lorsqu’une correction confirmée permettrait d’achever le traitement sans l’erreur signalée.