Writing values via Modbus not successful


using OH3 with KNX and Modus to read/ set values of my heat pump.
Since a couple of weeks a value ventilation will not set correctly. Before I had no issues…

In the following case I wanted to change the from ventilation from level 1 to 3 but the heat pump stays at 1… nothing is changing. Any idea?

2022-09-18 12:58:29.944 [INFO ] [openhab.event.ItemCommandEvent ] - Item ‘LWZ_Lueftung_StufeTag’ received command 3.0
2022-09-18 12:58:29.946 [INFO ] [penhab.event.ItemStatePredictedEvent] - Item ‘LWZ_Lueftung_StufeTag’ predicted to become 1.0

the rule is as follow

rule "Change FanLevel at HeatPump via ModBus"
        Item UG_HWR_Tecalor_Luefterstufe changed

thing as follow

Bridge poller isg_systemparameter [ start=1000, length=25, refresh=30000, type="holding" ] {
		Thing data LWZ_Lueftung_StufeTag "Lüftung Stufe Tag" [ readStart="1017", readValueType="uint16", readTransform="default", writeStart="1017", writeType="holding", writeValueType="uint16", writeTransform="default" ]

small change… ‘predicted to’ is corrected by using receivedCommand (instead of state.toString), but still the heat pump is changing to the value sent. Any idea?