Relative Size works on files - but not on folders

I'm looking for 60 Gb of files on a disk that only shows a 100 GB used. I thought relative size would help me find where are those 60Gb. Relative size displays files within folders and their relative size - but does not show the relative size of folders on a disk. Ideas?

See here: Calculate Folder Sizes Automatically

I've highlighted the folders>edit - I don't have the option edit>calculation folder size. Ctrl+L doesn't do anything either. I looked under custom commands and don't see it there either. What am I missing?

Are you using Opus 9 or 10?

v 10.0.5

Under edit my choices are:
copy filenames
select all
invert selection

that's all my edit choices.

You're not using the default toolbars then. You can either reset to the defaults or add the GetSizes command mentioned in the guide.

(Or you might have the command already in another location, depending on where your toolbars came from and how much you've edited them. The guide says where the button was located in Opus 9 if that was where your current toolbars originated.)

I see the option when I restore the default toolbars. I've customized DO in the past - but I don't see the option anywhere to add the ctrl+l command to my existing menu options or toolbars. How do I add the option of relative size to my existing toolbars or menus? Thanks!

If you go into Customize Toolbars mode, you can simply drag the item from the default toolbars into your own.

Or create a new button which runs the GetSizes command.