Ar_sendmail and gchart

Hi, first at all sorry if my english is not the best.
I write this topic because we have a problem with ar_sendmail after
install googlecharts gem.

In our server, if I comment this line in enviorenment.rb:
#require ‘gchart’

and I execute in console :
ar_sendmail

it works perfecly. But the problem begins when I uncoment the line in
enviorenment require ‘gchart’. If I execute ar_sendmail in console this
is tehe result:

ar_sendmail must be run from a Rails application’s root to deliver
email.
/var/www/vhosts/xxxx.net/releases/20090715065324 does not appear to be a
Rails application root.

Usage: ar_sendmail [options]

ar_sendmail scans the email table for new messages and sends them to the
website’s configured SMTP host.

ar_sendmail must be run from a Rails application’s root.

Sendmail options:
-b, --batch-size BATCH_SIZE Maximum number of emails to send
per delay
Default: Deliver all available
emails
–delay DELAY Delay between checks for new mail
in the database
Default: 60
.
.
.

I’m trying to investigate this lines with google:
ar_sendmail must be run from a Rails application’s root to deliver
email.
/var/www/vhosts/xxxx.net/releases/20090715065324 does not appear to be a
Rails application root.

but there is not so much information.

Someone can help me please?