error executing whenever gem..

gistfile1.txt

config/schedule.rb:5:in `block in initialize': undefined method `sudo' for #<Whe
never::JobList:0x00000001be50b8> (NoMethodError)
        from /var/lib/gems/1.9.1/gems/whenever-0.8.4/lib/whenever/job_list.rb:44
:in `every'
        from config/schedule.rb:3:in `initialize'
        from /var/lib/gems/1.9.1/gems/whenever-0.8.4/lib/whenever/job_list.rb:25
:in `instance_eval'
        from /var/lib/gems/1.9.1/gems/whenever-0.8.4/lib/whenever/job_list.rb:25
:in `initialize'
        from /var/lib/gems/1.9.1/gems/whenever-0.8.4/lib/whenever.rb:15:in `new'
        from /var/lib/gems/1.9.1/gems/whenever-0.8.4/lib/whenever.rb:15:in `cron
'
        from /var/lib/gems/1.9.1/gems/whenever-0.8.4/lib/whenever/command_line.r
b:40:in `run'
        from /var/lib/gems/1.9.1/gems/whenever-0.8.4/lib/whenever/command_line.r
b:7:in `execute'
        from /var/lib/gems/1.9.1/gems/whenever-0.8.4/bin/whenever:41:in `<top (r
equired)>'
        from /usr/local/bin/whenever:23:in `load'
        from /usr/local/bin/whenever:23:in `<main>'