How To Add A Search Filter To Windows Explorer

When I'm browsing local/network drives in Windows 7, the Search box (upper right in any Explorer window) only offers two filters "Date Modified" and "Size".

The "Add a Search Filter" is grayed out.

Here's some info on search filters that are available to be added-- but I haven''t figured out how to add them yet:

Date Created: Searches according to when the file was created. You can select the date (or a range of dates) from a mini-calendar that appears.

Kind: Search for files of a specific type as selected from the drop-down list that appears when you click the Kind option.

Type: Searches based on certain file types by extension, such as .pdf, .jpg, or .docx.

Name: Searches by filename. You can enter all or part of the filename in the search text box after the Name filter.

Tags: This filter lets you search for a file by the tags assigned to it. Enter one or more tags after the Tags filter in the Search text box.

Authors: Search for file by a particular author. Enter an author name after the Authors filter in the Search text box or select the name from the drop-down list that appears. (This filter is called Artists when searching audio files.)