Can't start service and log doesn't help

[Rubén Dávila]

Hi folks, I've the following configuration for Unicorn(Rails application server):

check process unicorn_staging_app.com
  with pidfile /var/www/vhosts/app.com/httpdocs/shared/pids/unicorn.pid

  start program = "/etc/init.d/unicorn start /etc/unicorn/app.com.conf"
  stop program = "/etc/init.d/unicorn stop /etc/unicorn/app.com.conf"
  if mem is greater than 300.0 MB for 1 cycles then restart # eating up memory?

  if cpu is greater than 50% for 2 cycles then alert # send an email to admin
  if cpu is greater than 80% for 3 cycles then restart # hung process?

  group app.com

Monit can stop the service but fail for start it, here is the log:

[CDT Sep 21 10:45:24] debug    : restart service 'unicorn_staging_app.com' on user request
[CDT Sep 21 10:45:24] info     : monit daemon at 5482 awakened
[CDT Sep 21 10:45:24] info     : Awakened by User defined signal 1
[CDT Sep 21 10:45:24] info     : 'unicorn_staging_app.com' trying to restart
[CDT Sep 21 10:45:24] info     : 'unicorn_staging_app.com' stop: /etc/init.d/unicorn

[CDT Sep 21 10:45:26] info     : 'unicorn_staging_app.com' start: /etc/init.d/unicorn
[CDT Sep 21 10:45:56] error    : 'unicorn_staging_app.com' failed to start

I can't find the reason for this problem, although the start program
 command "/etc/init.d/unicorn start /etc/unicorn/app.com.conf" starts 
the service fine, please any idea for this issue?

Regards.