Perhaps a little more detail on the script?
ImageCatalog.jsx is one of the preinstalled scripts that come with InDesign.
It does only gather the images at the first level of a selected directory and no images contained in sub-directories.
There is an enhanced version of that script by Hans Haesler, that does not have that limitation.
It's available in German and French. Written and tested for CS5, but should run also in CS6 and all CC versions.
You can download the German version called BilderKatalog from here:
"auch Unterordner" ("also scan subdirectories") is turned on by default.
Here a screenshot from the German BilderKatalog_514d.js UI after selecting a folder: