Sinatra with Postgres and ActiveRecord | Error Pushing to Heroku is: Invalid DATABASE_URL

I have an application written in Sinatra that works locally but that I cannot seem to push up to heroku. When I attempt to push to heroku I get the following error: -----> Writing config/database.yml to read from DATABASE_URL Could not detect rake tasks ensure you can run $ bundle exec rake -P against your app with no environment variables present and using the production group of your Gemfile. Th

[yyamano]

“db = URI.parse(ENV['DATABASE_URL'] || 'postgres://localhost/calendar_development') ”