Edit Effective_Date

I'm trying to edit "Effective_Date", but get an error " The specified value for property Effective Date '01/17/2018 01:17:58 PM' of MIN_Delivered_Component does not match the required format. String today_str = DateTime.Now.ToString("MM/dd/yyyy hh:mm:ss tt"); Item DeliveredComponent = this.newItem("MIN_Delivered_Component","edit"); DeliveredComponent.setID(fullBOM.getItemByIndex(i).getRelatedItemID()); DeliveredComponent.setProperty("effective_date",today_str); DeliveredComponent = DeliveredComponent.apply();