Redmine

Hello.
I am in trouble with installing the redmine_issue_templates and looking for help. Sorry for my poor English ...
I clone the repo from github directly and bundle install without problem,but when I try to rake, bad things occurred.
What I did:

bundle exec rake redmine:plugins NAME=redmine_contacts RAILS_ENV=production

and the result is

rake aborted!
LoadError: cannot load such file -- yard
/usr/share/redmine/plugins/redmine_issue_templates/Rakefile:3:in `require'
/usr/share/redmine/plugins/redmine_issue_templates/Rakefile:3:in `<top (required)>'
/var/lib/gems/2.3.0/gems/rake-11.2.2/exe/rake:27:in `<top (required)>'
/var/lib/gems/2.3.0/gems/bundler-1.12.5/lib/bundler/cli/exec.rb:63:in `load'
/var/lib/gems/2.3.0/gems/bundler-1.12.5/lib/bundler/cli/exec.rb:63:in `kernel_load'
/var/lib/gems/2.3.0/gems/bundler-1.12.5/lib/bundler/cli/exec.rb:24:in `run'
/var/lib/gems/2.3.0/gems/bundler-1.12.5/lib/bundler/cli.rb:304:in `exec'
/var/lib/gems/2.3.0/gems/bundler-1.12.5/lib/bundler/vendor/thor/lib/thor/command.rb:27:in `run'
/var/lib/gems/2.3.0/gems/bundler-1.12.5/lib/bundler/vendor/thor/lib/thor/invocation.rb:126:in `invoke_command'
/var/lib/gems/2.3.0/gems/bundler-1.12.5/lib/bundler/vendor/thor/lib/thor.rb:359:in `dispatch'
/var/lib/gems/2.3.0/gems/bundler-1.12.5/lib/bundler/vendor/thor/lib/thor/base.rb:440:in `start'
/var/lib/gems/2.3.0/gems/bundler-1.12.5/lib/bundler/cli.rb:11:in `start'
/var/lib/gems/2.3.0/gems/bundler-1.12.5/exe/bundle:27:in `block in <top (required)>'
/var/lib/gems/2.3.0/gems/bundler-1.12.5/lib/bundler/friendly_errors.rb:98:in `with_friendly_errors'
/var/lib/gems/2.3.0/gems/bundler-1.12.5/exe/bundle:19:in `<top (required)>'
/usr/local/bin/bundle:23:in `load'
/usr/local/bin/bundle:23:in `<main>'
(See full trace by running task with --trace)

The content of my Rakefile if below:

require 'rake'
require 'rake/testtask'
require 'yard'

desc 'Default: run unit tests.'
task default: :test

desc 'Test the redmine_banner plugin.'
Rake::TestTask.new(:test) do |t|
  t.libs << 'lib'
  t.pattern = 'test/**/*_test.rb'
  t.verbose = true
end

YARD::Rake::YardocTask.new(:yardoc) do |t|
  files = ['lib/**/*.rb', 'app/**/*.rb'] # exclude test file
  t.files = files
  t.options += ['--output-dir', './doc']
end

So I try to gem install yard and succeed, but didn`t work and my redmine version is 3.2.1.

Thanks for your reading!