Setting the zoom of Sony RX100M7 ?

Hi,

I am trying to set a certain zoom of the RX100M7 and where I can set 
other values, I get this for getting:

gphoto2 --get-config /main/capturesettings/zoom
Label: Zoom
Readonly: 0
Type: RANGE
Current: 23,4629
Bottom: 0
Top: 4294,97
Step: 1
END

And for setting:
gphoto2 --set-config /main/capturesettings/zoom=24
*** Error ***
PTP Device Busy

How should I interpret this? I get the feeling that the specified value 
is incorrect... How should I set this value? Or where can I learn how to 
find the possible values for --set-config?

The camera works fine for e.g.
gphoto2 --set-config /main/capturesettings/shutterspeed=18

Thanks!
Raymond