couchbase Client Time out with ruby 1.9.3

After we upgrade to rails 3.2.8 with ruby 1.9.3 (from 1.8.7), our couchbase client could no longer access our AWS cluster (couchbase 1.8 community edition).

1.9.3p194 :011 > c = Couchbase.new("http://ec2-184-169-237-63.us-west-1.compute.amazonaws.com:8091")
=> #

1.9.3p194 :012 > c.get("hello")
Couchbase::Error::Timeout: failed to get value (key="hello", error=0x16)
from (irb):12:in `get'
from (irb):12
from /Users/playmeshinc/.rvm/gems/ruby-1.9.3-p194/gems/railties-3.2.8/lib/rails/commands/console.rb:47:in `start'
from /Users/playmeshinc/.rvm/gems/ruby-1.9.3-p194/gems/railties-3.2.8/lib/rails/commands/console.rb:8:in `start'
from /Users/playmeshinc/.rvm/gems/ruby-1.9.3-p194/gems/railties-3.2.8/lib/rails/commands.rb:41:in `'
from script/rails:6:in `require'
from script/rails:6:in `'

On the admin panel, we cannot even see any request reaching the server.

However, if we use the memcache protocol on port 11211, everything works well. If we try the same code and same call on our local couchbase cluster (osx), things works just fine.

Any idea what might have happened? Is that because ruby couchbase client is not compatible with AWS or ruby 1.9.3?

Many Thanks.