recovery of values from mqtt

good evening to all, I would like to recover some mqtt values from a sonoff-dual. specifically the value SHUTTER1
18:48:21 MQT: tasmota/bagno_gianni/serranda/stat/SHUTTER1 = 9
I’m trying to put this code in the .items file but nothing
Number LivingRoom_Light_RSSI “Living Room Light: RSSI [%d %%]” (gRSSI)
{ mqtt="
<[openhabianpi-mqtt:tasmota/bagno_gianni/serranda/TELE:STATE:SENSOR:JSONPATH($.SHUTTER-1.RSSI) ]"
can you tell me where I’m wrong?
Thank you

Which MQTT binding are you using? MQTTv1 or MQTTv2?

Shouldn’t it be something like:

{ mqtt="
<[openhabianpi-mqtt:tasmota/bagno_gianni/serranda/stat/SHUTTER1 ]"

I’m using mqqt 1
for completeness I need the value Shutter-1 which indicates the percentage value of the opening of the shutter.
@opus I tried but gives me the following error:

2019-02-03 19:37:59.497 [ERROR] [el.item.internal.GenericItemProvider] - Binding configuration of type 'mqtt' of item 'LivingRoom_Light_RSSI' could not be parsed correctly.

Try this for the wifi RSSI.

Number LivingRoom_Light_RSSI "Living Room Light: RSSI [%d %%]" (gRSSI)
	{ mqtt="<[openhabianpi-mqtt:tele/tasmota/bagno_gianni/serranda/STATE:state:JSONPATH($.Wifi.RSSI)]" }