public event AccountOrderTradeEventHandler OrderTradePublic Event OrderTrade As AccountOrderTradeEventHandlerOccurs when an order gets filled, either partially or completely. This event will be raised for each fill the order gets so a 10 lot order that gets filled in two 5 lots will receive two OrderFill events, even if the fill prices are the same.
The OrderUpdate event is also called when an order receives a fill.
If an order gets filled while the API is disconnected from the server then you will NOT get an OrderFill event. You either need to check the order details individually or check the Position details.