tile_translate: No suitable tile layer found

I running on Fedora 19 with postgis-2.0.3-1, postgresql-9.2.6, mapnik-2.0.2 and osm2pgsql-0.82.0-3. I create a database. Cloned mapnik-stylesheets. Cloned, built and installed mod_tile. I run 'renderd -f' then in the browser hit slippymap.html but the apache log says things like:

[Thu Dec 26 16:20:05.506318 2013] [core:info] [pid 12644] [client ::1:44050] AH00128: File does not exist: /var/www/html/10/536/359.png, referer: http://localhost/slippymap.html
[Thu Dec 26 16:20:05.506410 2013] [tile:debug] [pid 12637] ./src/mod_tile.c(1278): [client ::1:44047] tile_translate: uri(/10/536/355.png), referer: http://localhost/slippymap.html
[Thu Dec 26 16:20:05.506430 2013] [tile:debug] [pid 12637] ./src/mod_tile.c(1296): [client ::1:44047] tile_translate: testing baseuri(/osm_tiles/) name(default) extension(png), referer: http://localhost/slippymap.html
[Thu Dec 26 16:20:05.506447 2013] [tile:debug] [pid 12637] ./src/mod_tile.c(1386): [client ::1:44047] tile_translate: No suitable tile layer found, referer: http://localhost/slippymap.html
[Thu Dec 26 16:20:05.506489 2013] [authz_core:debug] [pid 12637] mod_authz_core.c(802): [client ::1:44047] AH01626: authorization result of Require all granted: granted, referer: http://localhost/slippymap.html
[Thu Dec 26 16:20:05.506513 2013] [authz_core:debug] [pid 12637] mod_authz_core.c(802): [client ::1:44047] AH01626: authorization result of <RequireAny>: granted, referer: http://localhost/slippymap.html
[Thu Dec 26 16:20:05.506541 2013] [core:info] [pid 12637] [client ::1:44047] AH00128: File does not exist: /var/www/html/10/536/355.png, referer: http://localhost/slippymap.html

There's something I'm not understanding about the configuration because I'm not seeing any output from renderd. It doesn't appear that mod_tile and renderd are talking. Apache and renderd are running as the apache user who owns /var/run/renderd and its contents. Here's my renderd.conf:

[renderd]
socketname=/var/run/renderd/renderd.sock
num_threads=4
tile_dir=/home/mod_tile
stats_file=/var/run/renderd/renderd.stats

[mapnik]
plugins_dir=/usr/lib64/mapnik/input
font_dir=/usr/share/fonts/dejavu
font_dir_recurse=1

[default]
URI=/osm_tiles/
TILEDIR=/home/mod_tile
XML=/home/apache/mapnik-stylesheets/osm.xml
HOST=127.0.0.1
TILESIZE=256

And I'm using pretty much the stock mod_tile.conf which I dropped into /etc/httpd/conf.d. Can anyone help me understand/debug this problem?