Set blind slat position via vis (Homematic IP)

[Matthias_]

Hello, I have created a test virtualization with which I want to control various blinds. Everything works as it should except for setting the slat position. To set the slat position I change the value Level_2.
Unfortunately the slat position doesn't change at all and the CCU3 still shows the value that was set by CCU3 bevor. I noticed that when I change the value via Vis, the parameter Confirmed is set to false, maybe it has something to do with it? If so can the parameter also be set to true?
Thanks in advance
nice greetings Matthias