Ah, yes, that was the problem. Thanks for the suggestion.
Of course, since nothing can ever be easy, it took me a little time to figure out how to turn on mod_rewrite. What I had to do was edit the http configuration (for Centos, it is in /etc/httpd/conf/httpd.conf. )
Under the <Directory “[my documentroot]”>
The default is:
AllowOverride None
Change it to:
AllowOverride All
Then restart apache (service httpd restart)
That got it working for me.