Set scale of oscilloscope via TekVISA

I have downloaded the driver for the Tektronik MSO 4104 from Mathworks. I can get the data and can change the window-timebase.

So the connection to the oscilloscope is established and working.

But I have problems when I want to set the scale of the oscilloscope:

My course of action:

I have opened the "tmtool" and created a new Device Object by using the driver.

Then I have chosen the property "Scale".

At this moment there is an error message:

"The dependent property Probe was not found while saving the Scale property in the channel group."

Then I tried a different approach:

I opened the deviceOBJ (double click on deviceObj in the Workspace) and chose "Channel", then I wanted to increase the Scale.

This caused an Exception:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException

What am I doing wrong?

Or is there a other way to set the scale?