Locations in Smart Folders

Hi folks. Smart Folders isn't working the way I expected, so I need to ask.

I want to qualify all the labelled files within a main directory. Several folders deep, all files labelled purple.

I have a new Smart Folder with File Label: purple, but I'm not sure what to put in location. Is that the top directory name? Is it a posix path? Neither worked for me. The files show up when just the File Label is chosen, but when anything is entered for location, everything disappears.

Any help appreciated.

Cheers