Slider item does not understand IN/DECRESE commands

[3DJupp (Dominic Spatz)]

I got the slider configured in the HABdroid and iPhone Application.
But in the Classic UI the two setpoint arrows for the slider won’t work.

Error
Received unknown command 'INCREASE' for item 'TV_Volume'

How can i use the slider item in a browser?
I use OpenHAB2 and the SamsungTV Binding that is available for OpenHAB2

Items:
Number TV_Volume "Volume" {channel="samsungtv:tv:UID:channel"}

Sitemap:
Slider item=TV_Volume icon="audio_shuffle_64" label="Volume"

I hope that you might have a hint for that issue.

An older topic which was OH1.x related had a similar issue

Sharp Aquos TV Help?

Hi All! So I integrated my 70" sharp aquos tv into OH with Power and inputs etc. I am working now on the volume which works if i set an actual number. What I need is some way to increment the number like with the setpoint command preferably. my current setup is this, Items: Rollershutter Volume “TV Volume” (LivingRoom) { sharptv = “uid=livingroom, bindingType=volume” } sitemap: Switch item=Volume label=“Volume Up/Down” mappings=[20=“UP”, 0=“DOWN”] Thanks!!!