How can I log rewrite errors with apache 2.4?

I have a RewriteRule that is not working. So I want to look at a log file for clues about what went wrong. Here is what I tried. I used WHM to edit the apache global config by setting log level to "debug" and Trace enable to "extended. I saved the settings, remade and restarted apache. Then I browsed to the page that should have redirected. The redirect did not work. So I looked in the apache error.log file and searched for "rewrite". That string was not found. Any suggestions for how to get rewrite errors to show up in a log somewhere when using apache 2.4? What documentation do I need to read? My googling was not turning up an answer.