knife data bag from file -- uninitialized constant

knife data bag from file somebag blah.json
/Users/dje/.rvm/gems/ruby-1.9.2-p180/gems/chef-0.10.0.beta.3/lib/chef/knife.rb:316:in `load_from_file': uninitialized constant Chef::Role (NameError)
from /Users/dje/.rvm/gems/ruby-1.9.2-p180/gems/chef-0.10.0.beta.3/lib/chef/knife/data_bag_from_file.rb:66:in `run'
from /Users/dje/.rvm/gems/ruby-1.9.2-p180/gems/chef-0.10.0.beta.3/lib/chef/knife.rb:157:in `run'
from /Users/dje/.rvm/gems/ruby-1.9.2-p180/gems/chef-0.10.0.beta.3/lib/chef/application/knife.rb:119:in `run'
from /Users/dje/.rvm/gems/ruby-1.9.2-p180/gems/chef-0.10.0.beta.3/bin/knife:25:in `<top (required)>'
from /Users/dje/.rvm/gems/ruby-1.9.2-p180/bin/knife:19:in `load'
from /Users/dje/.rvm/gems/ruby-1.9.2-p180/bin/knife:19:in `<main>'