Notification for Fire TV not working

[DivineJimmi]

I am unable to use the notification for fire TV Binding.

I did exactly as the docs said, and its not working. Trying with an android app works witthout any circumstances. When firing the rule, the thing turns offline for a few seconds and then back online.

The thing initially turn online and is probably correct connected.

rule "Test"
when
    //something happens
then
    val notificationsForFireTVActions = getActions("notificationsforfiretv","notificationsforfiretv:notification:b385c5f0f9")
    var boolean success = notificationsForFireTVActions.sendNotification("This is the notification content.", "/etc/openhab/icons/classic/motionsensor.png")
end

log:

Thing 'notificationsforfiretv:notification:b385c5f0f9' changed from ONLINE to OFFLINE (COMMUNICATION_ERROR): Unable to connect to server: 400
Thing 'notificationsforfiretv:notification:b385c5f0f9' changed from OFFLINE (COMMUNICATION_ERROR): Unable to connect to server: 400 to OFFLINE (COMMUNICATION_ERROR): fixed content-length: 123, bytes received: 0
Thing 'notificationsforfiretv:notification:b385c5f0f9' changed from OFFLINE (COMMUNICATION_ERROR): fixed content-length: 123, bytes received: 0 to OFFLINE (COMMUNICATION_ERROR): Unable to connect to server: 400
Thing 'notificationsforfiretv:notification:b385c5f0f9' changed from OFFLINE (COMMUNICATION_ERROR): Unable to connect to server: 400 to ONLINE

Not working at all.