"Your pictures are super-low resolution, so difficult to see the details, but if I see this correctly, you have the source A set to "None" for your channel. You'll need to assign channel 10 to a physical input (routing page), then you should get a gain slider.
Cheers,
Torsten"
Thanks Torsten, that makes perfect sense. I'll check the I/O routing, but I'm sure you've hit the nail on the head.
Thanks
Rob