Topic: works fine at localhost, but get application at heroku server

Hi all,
I am new at RoR.
I have created a demo application which is runs using "rails server". But when I tried with "git push heroku master" it gets "Application error" at ###.heroku.com site. Log file shows following message:

....
2012-03-26T06:11:23+00:00 app[web.1]:     from /usr/ruby1.9.2/lib/ruby/gems/1.9.1/gems/thin-1.2.6/lib/thin/runner.rb:177:in `run_command'
2012-03-26T06:11:23+00:00 app[web.1]:     from /usr/ruby1.9.2/lib/ruby/gems/1.9.1/gems/thin-1.2.6/lib/thin/runner.rb:143:in `run!'
2012-03-26T06:11:23+00:00 app[web.1]:     from /usr/ruby1.9.2/lib/ruby/gems/1.9.1/gems/thin-1.2.6/bin/thin:6:in `<top (required)>'
2012-03-26T06:11:23+00:00 app[web.1]:     from /usr/ruby1.9.2/bin/thin:19:in `load'
2012-03-26T06:11:23+00:00 app[web.1]:     from /usr/ruby1.9.2/bin/thin:19:in `<main>'
2012-03-26T06:11:24+00:00 heroku[web.1]: Process exited with status 1
2012-03-26T06:11:24+00:00 heroku[web.1]: State changed from starting to crashed
2012-03-26T06:19:10+00:00 heroku[router]: Error H10 (App crashed) -> GET deep-snow-3933.heroku.com/ dyno= queue= wait= service= status=503 bytes=
2012-03-26T06:19:10+00:00 heroku[nginx]: 133.11.102.2 - - [26/Mar/2012:06:19:10 +0000] "GET / HTTP/1.1" 503 607 "-" "Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.0.15) Gecko/2009102704 Fedora/3.0.15-1.fc10 Firefox/3.0.15" deep-snow-3933.heroku.com
[first_app (master)]$


available gems are:

*** LOCAL GEMS ***

abstract (1.0.0)
actionmailer (3.0.1, 3.0.0, 3.0.0.rc)
actionpack (3.0.1, 3.0.0, 3.0.0.rc)
activemodel (3.2.2, 3.0.1, 3.0.0, 3.0.0.rc)
activerecord (3.0.1, 3.0.0, 3.0.0.rc)
activeresource (3.0.1, 3.0.0, 3.0.0.rc)
activesupport (3.2.2, 3.0.1, 3.0.0, 3.0.0.rc)
addressable (2.2.7)
arel (3.0.2, 1.0.1, 0.4.0)
builder (3.0.0, 2.1.2)
bundler (1.1.3, 1.1.2, 1.0.22)
daemons (1.1.8)
erubis (2.6.6)
eventmachine (0.12.10)
heroku (2.22.0)
i18n (0.6.0, 0.4.2)
launchy (2.1.0)
mail (2.2.19)
mime-types (1.18)
multi_json (1.1.0)
netrc (0.7.1)
polyglot (0.3.3)
rack (1.2.5)
rack-mount (0.6.14)
rack-test (0.5.7)
rails (3.0.1, 3.0.0.rc)
railties (3.0.1, 3.0.0, 3.0.0.rc)
rake (0.9.2.2)
rest-client (1.6.7)
rubygems-bundler (0.2.8)
rubyzip (0.9.6.1)
searchlogic (2.3.5)
sqlite3-ruby (1.2.5)
thin (1.3.1)
thor (0.14.6)
treetop (1.4.10)
tzinfo (0.3.32)

With advanced thanking
mhossain