Segment statistics-PET volume statistics

Operating system: Windows 11 home
Slicer version:4.13.0-2021-12-22

I would like to calculate 42% SUVmax of the given segmented region. But from segment statistics module, I am unable to calculate the PET volume statistics. I can only see surface area and volume being calculated. I am not sure where I have gone wrong in this.
Sharing a picture of my screen.

Thanks in advance