scm 'subversion' doesn't work

[maize]

Here my deploy block:

deploy "/srv/#{appname}" do
repo "###"
svn_username "###"
svn_password "###"
scm 'subversion'
branch node[:rails_app_name][:branch]
user "root"
group "root"
migrate node[:rails_app_name][:migrate]
migration_command node[:rails_app_name][:migrate_command]
environment node[:rails_app_name][:environment]
revision node[:rails_app_name][:revision]
action node[:rails_app_name][:action].to_sym
restart_command "touch tmp/restart.txt"
action :deploy
end

I always get this error:
"/var/lib/gems/1.8/gems/chef-0.8.6/bin/../lib/chef/resource.rb:74:in method_missing': undefined methodscm' for Chef::Resource::Deploy (NoMethodError)"