shouldn't the 51 bytes bar be hardly visible ?
Not if the top two things are folders and the bottom thing is a file, but the screenshot is so cropped we can't even see the whole bars. 
okay. Thanks. I have same colours set for files & folders, will change them 
Turn off Preferences / Miscellaneous / Advanced [Information Display]: graphs_separate_files_dirs if you want the graphs to treat files and folders the same.
You guys have thought of everything!