Mongowatch not working

Hi everybody:
I have installed mongowatch to monitor mongodb,when I run the command
"ruby mongo_watch.rb",it prints the following messages:

/usr/lib/ruby/1.8/net/http.rb:560:in `initialize': Connection refused - connect(2) (Errno::ECONNREFUSED)
from /usr/lib/ruby/1.8/net/http.rb:560:in `open'
from /usr/lib/ruby/1.8/net/http.rb:560:in `connect'
from /usr/lib/ruby/1.8/timeout.rb:53:in `timeout'
from /usr/lib/ruby/1.8/timeout.rb:93:in `timeout'
from /usr/lib/ruby/1.8/net/http.rb:560:in `connect'
from /usr/lib/ruby/1.8/net/http.rb:553:in `do_start'
from /usr/lib/ruby/1.8/net/http.rb:542:in `start'
from /usr/lib/ruby/1.8/net/http.rb:1035:in `request'
from /usr/lib/ruby/1.8/net/http.rb:992:in `request_post'
from mongo_watch.rb:36:in `post'
from mongo_watch.rb:28:in `send_data'
from mongo_watch.rb:63
from mongo_watch.rb:58:in `each'
from mongo_watch.rb:58

anyone can resolve the problem???
Thanks