Commands which generate a list of buttons (e.g. Go DRIVEBUTTONS) can only be used on their own; they can't be combined with other normal commands (e.g. Set SOURCE=left).
You could work around this by creating an individual button for each drive, which runs something like this:
Thanks for your explanation. I though it was something like some sort of special behaviour.
I've got used to this behaviour in Total Commander. In TC when you have dual drive buttons it also automatically sets source to appropriate panel.
Now I switched to dopus after 10 years of TC and I have problems with my habit