Map not displayed in the browser and mod_tile folder is empty

Dear all

I follow the article( and install the openstreetmap on Ubuntu.

I start the tileserver and apache use the following command.

sudo mkdir /var/run/renderd
sudo chown username /var/run/renderd
renderd -f -c /usr/local/etc/renderd.conf

sudo /etc/init.d/apache2 restart

But I can’t browser the picture at
Can somebody help me to solve the problem?The log as below.
p.s I didn’t download the all planet map.I only download and import sub-region Syria from
Thank you very much!

renderd[2587]: Rendering daemon started
renderd[2587]: Initiating reqyest_queue
renderd[2587]: Parsing section renderd
renderd[2587]: Parsing render section 0
renderd[2587]: Parsing section mapnik
renderd[2587]: Parsing section default
renderd[2587]: config renderd: unix socketname=/var/run/renderd/renderd.sock
renderd[2587]: config renderd: num_threads=4
renderd[2587]: config renderd: num_slaves=0
renderd[2587]: config renderd: tile_dir=/var/lib/mod_tile
renderd[2587]: config renderd: stats_file=(null)
renderd[2587]: config mapnik:  plugins_dir=/usr/local/lib/mapnik/input
renderd[2587]: config mapnik:  font_dir=/usr/share/fonts/truetype/unifont
renderd[2587]: config mapnik:  font_dir_recurse=1
renderd[2587]: config renderd(0): Active
renderd[2587]: config renderd(0): unix socketname=/var/run/renderd/renderd.sock
renderd[2587]: config renderd(0): num_threads=4
renderd[2587]: config renderd(0): tile_dir=/var/lib/mod_tile
renderd[2587]: config renderd(0): stats_file=(null)
renderd[2587]: config map 0:   name(default) file() uri(/osm_tiles/) htcp() host(localhost)
renderd[2587]: Initialising unix server socket on /var/run/renderd/renderd.sock
renderd[2587]: Created server socket 4
renderd[2587]: Renderd is using mapnik version 2.0.3
renderd[2587]: DEBUG: Loading font: /usr/share/fonts/truetype/unifont/unifont.ttf
Running in foreground mode...
renderd[2587]: No stats file specified in config. Stats reporting disabled
renderd[2587]: DEBUG: Got incoming connection, fd 7, number 1
renderd[2587]: DEBUG: Got incoming request with protocol version 2
renderd[2587]: DEBUG: Got command RenderPrio fd(7) xml(default), z(0), x(0), y(0), mime(image/png), options()
renderd[2587]: No map for: default
renderd[2587]: DEBUG: Failed to read cmd on fd 7
renderd[2587]: DEBUG: Connection 0, fd 7 closed, now 0 left