MAInternalEditorComponent error

Hi, i work with Magritte-Model-lr.394 on pharo. I have a MAAccountModel with descriptionCodice and descriptionIndirizzoMemo. The last is defined as: descriptionIndirizzoMemo ^ (MAToOneRelationDescription new) componentClass: MAInternalEditorComponent ; classes: (Array with: MAIndirizzoModel); selectorAccessor: 'indirizzoMemo'; label: 'Indirizzo'; comment: 'Indirizzo di riferimento'; priority: 220; "beReadonly;" yourself Now MAIndirizzoMemoModel is defined with some other description: descrptionCitta descriptionNumero and other description. ( You can load the file mcz. ) Now when open: MAAccountModel new asComponent i found the error: MessageNotUnderstood: receiver of "isMultipart" is nil isMultipart ^ self children anySatisfy: [ :each | each isMultipart ] The error is erase only with componentClass set to : MAInternalEditorComponent. Any considerations ? Thanks, Dario