Apple Mail Search Option Not Working

I can't seem to get the search function in the Apple Mail to work properly. When I search any mailbox using the search field in the upper right corner of the window, there are no results. I used all kinds of search terms and selecting the "From, To, Subject, Mailbox, Attachment, and Entire Message" options and nothing appears. I can't identify the setting to correct this.

And this is on what Mac and using what operating system? Vital information required.