How do I enable a field when clicking on an action?

The requirement is to enable the Customer Order Nbr when a new action ‘Change Order Nbr’ is selected. I created the below action method. It is executed on clicking the action but the field is not enabled. This is after the invoice was Released. 

public PXAction<ARInvoice> ChangeOrderNbr;
        [PXButton(CommitChanges = true)]
        [PXUIField(DisplayName = "Change Order Nbr", Enabled = false, MapEnableRights = PXCacheRights.Delete, MapViewRights = PXCacheRights.Delete)]
        protected virtual void changeOrderNbr()
        {
            PXUIFieldAttribute.SetEnabled<ARInvoice.invoiceNbr>(base.Base.CurrentDocument.Cache, base.Base.Document.Current, true);

            // Trigger the Save action to save changes in the database.
            // base.Base.Actions.PressSave();
        }