RFXCom binding ACK

Hi. I have OpenHab with a RFXCom. Openhab can communicate with my RFXCom and I can turn On my light but I don’t receive an ACK and I cannot turn OFF my light. here my log:
2016-12-14 20:41:13.990 [TRACE] [c.a.internal.AutoUpdateBinding] - Won’t update item ‘Lumiere_Salon_TV’ as it is not configured to update its state automatically.
2016-12-14 20:41:14.011 [DEBUG] [.rfxcom.internal.RFXComBinding] - Received command: Lumiere_Salon_TV ON
2016-12-14 20:41:14.012 [DEBUG] [.rfxcom.internal.RFXComBinding] - Received command (item=‘Lumiere_Salon_TV’, state=‘ON’, class=‘class org.openhab.core.library.types.OnOffType’)
2016-12-14 20:41:14.013 [DEBUG] [.rfxcom.internal.RFXComBinding] - Transmitting data: 0B1100020100569E01010000
2016-12-14 20:41:14.577 [TRACE] [.b.r.i.c.RFXComSerialConnector] - Received data (len=1): 04
2016-12-14 20:41:14.578 [TRACE] [.b.r.i.c.RFXComSerialConnector] - Received data (len=1): 00
2016-12-14 20:41:19.015 [ERROR] [.rfxcom.internal.RFXComBinding] - No acknowledge received from RFXCOM controller, timeout 5000ms due to java.util.concurrent.TimeoutException: waiting timed out

Firmware of my RFXcom is 1011, OpenHab 1.8.0 and it is on a QNAP TS439.