Dev env Seafile server startup error。

I built development environment via guide https://manual.seafile.com/develop/env.html, when I tried to start sealfile-server with command seaf-server -c conf -d conf/seafile-data -f -l - , I got error like,
[01/25/17 12:07:45] seafile-session.c(77): Failed to load config file.
[01/25/17 12:07:45] seaf-server.c(978): Failed to create seafile session.
Any proposal from you can help me to fix it, btw, where is the log path for develop env?