td-agentのfluent-plugin-cloudwatch-logsの使い方について

http://blog.cloudpack.jp/2014/07/23/aws-fluent-plugin-cloudwatch/

上記のサイトを参考に、td-agentを使って、
AWS の cloudwatch-logs のログを取得しようとしています。
単純に td-agent とコマンドを実行すると、ログが取得できるのですが、
service td-agent start , /etc/init.d/td-agent start として
実行すると、cloudwatch-logs のログが取得できなくなります。

ログにはエラーが出ていないので、原因が分からずにいます。
どなたか解決方法を御存じの方はいらっしゃいますでしょうか。

■環境情報

bash
1# cat /etc/redhat-release
2CentOS release 6.7 (Final)
3# ruby -v
4ruby 1.8.7 (2013-06-27 patchlevel 374) [x86_64-linux]
5
6# td-agent --version
7td-agent 0.10.55
8
9# gem -v
101.3.7
11
12・プラグインの一覧
13# cd /usr/lib64/fluent/ruby/lib/ruby/gems/1.9.1/gems/
14# ls -1
15aws-sdk-1.52.0
16aws-sdk-2.2.5
17aws-sdk-core-2.2.5
18aws-sdk-resources-2.2.5
19aws-sdk-v1-1.52.0
20aws-sdk-v1-1.56.0
21bson-1.11.1
22bson-1.8.6
23bson_ext-1.8.6
24bundler-1.3.6
25cool.io-1.1.1
26cool.io-1.4.2
27diff-lcs-1.2.5
28fluentd-0.10.55
29fluent-logger-0.4.9
30fluent-mixin-config-placeholders-0.2.4
31fluent-mixin-config-placeholders-0.3.0
32fluent-mixin-plaintextformatter-0.2.6
33fluent-plugin-cloudwatch-logs-0.1.2
34fluent-plugin-flume-0.1.1
35fluent-plugin-mongo-0.7.3
36fluent-plugin-rewrite-tag-filter-1.4.1
37fluent-plugin-s3-0.4.1
38fluent-plugin-scribe-0.10.12
39fluent-plugin-td-0.10.22
40fluent-plugin-td-monitoring-0.1.3
41fluent-plugin-webhdfs-0.3.1
42git-1.2.8
43hirb-0.7.2
44httpclient-2.3.4.1
45httpclient-2.4.0
46http_parser.rb-0.5.1
47iobuffer-1.1.2
48ipaddress-0.8.0
49jeweler-1.6.2
50jmespath-1.1.3
51json-1.7.7
52ltsv-0.1.0
53mini_portile-0.6.0
54mixlib-cli-1.5.0
55mixlib-config-2.1.0
56mixlib-log-1.6.0
57mixlib-shellout-1.6.0
58mongo-1.8.6
59msgpack-0.4.7
60msgpack-0.5.12
61nokogiri-1.5.10
62ohai-6.20.0
63parallel-0.6.5
64rake-0.9.2.2
65rdoc-3.9.5
66rspec-3.0.0
67rspec-core-3.0.4
68rspec-expectations-3.0.4
69rspec-mocks-3.0.4
70rspec-support-3.0.4
71rubyzip-0.9.9
72sigdump-0.2.2
73string-scrub-0.0.3
74systemu-2.5.2
75td-0.11.5
76td-client-0.8.66
77td-logger-0.3.23
78thread_safe-0.3.5
79thrift-0.8.0
80tzinfo-1.2.2
81tzinfo-data-1.2015.7
82uuidtools-2.1.5
83webhdfs-0.5.5
84yajl-ruby-1.1.0
85
86■td-agent 設定ファイル
87# cat td-agent.conf
88<source>
89  type monitor_agent
90  bind 0.0.0.0
91  port 24220
92</source>
93include conf.d/*.conf
94
95# cat cloudwatch-logs.conf
96<source>
97  type forward
98</source>
99
100<source>
101  type cloudwatch_logs
102  tag test.cloudwatch_logs.in
103  log_group_name fluent-plugin-cloudwatch-example
104  log_stream_name fluent-plugin-cloudwatch-example
105  state_file /tmp/fluent-plugin-cloudwatch-example.state
106</source>
107
108<match test.cloudwatch_logs.in>
109  type file
110  path /tmp/cloudwatch_logs
111</match>
112
113■td-agent起動時のログ
114※起動コマンド /etc/init.d/td-agent start
115～～～～～
1162015-12-15 10:10:11 +0900 [info]: starting fluentd-0.10.55
1172015-12-15 10:10:11 +0900 [info]: reading config file path="/etc/td-agent/td-agent.conf"
1182015-12-15 10:10:11 +0900 [info]: gem 'fluent-mixin-config-placeholders' version '0.3.0'
1192015-12-15 10:10:11 +0900 [info]: gem 'fluent-mixin-config-placeholders' version '0.2.4'
1202015-12-15 10:10:11 +0900 [info]: gem 'fluent-mixin-plaintextformatter' version '0.2.6'
1212015-12-15 10:10:11 +0900 [info]: gem 'fluent-plugin-cloudwatch-logs' version '0.1.2'
1222015-12-15 10:10:11 +0900 [info]: gem 'fluent-plugin-flume' version '0.1.1'
1232015-12-15 10:10:11 +0900 [info]: gem 'fluent-plugin-mongo' version '0.7.3'
1242015-12-15 10:10:11 +0900 [info]: gem 'fluent-plugin-rewrite-tag-filter' version '1.4.1'
1252015-12-15 10:10:11 +0900 [info]: gem 'fluent-plugin-s3' version '0.4.1'
1262015-12-15 10:10:11 +0900 [info]: gem 'fluent-plugin-scribe' version '0.10.12'
1272015-12-15 10:10:11 +0900 [info]: gem 'fluent-plugin-td' version '0.10.22'
1282015-12-15 10:10:11 +0900 [info]: gem 'fluent-plugin-td-monitoring' version '0.1.3'
1292015-12-15 10:10:11 +0900 [info]: gem 'fluent-plugin-webhdfs' version '0.3.1'
1302015-12-15 10:10:11 +0900 [info]: gem 'fluentd' version '0.10.55'
1312015-12-15 10:10:11 +0900 [info]: using configuration file: <ROOT>
132  <source>
133    type monitor_agent
134    bind 0.0.0.0
135    port 24220
136  </source>
137  <source>
138    type forward
139  </source>
140  <source>
141    type cloudwatch_logs
142    tag test.cloudwatch_logs.in
143    log_group_name fluent-plugin-cloudwatch-example
144    log_stream_name fluent-plugin-cloudwatch-example
145    state_file /tmp/fluent-plugin-cloudwatch-example.state
146  </source>
147  <match test.cloudwatch_logs.in>
148    type file
149    path /tmp/cloudwatch_logs
150  </match>
151</ROOT>
1522015-12-15 10:10:11 +0900 [info]: adding source type="monitor_agent"
1532015-12-15 10:10:11 +0900 [info]: adding source type="forward"
1542015-12-15 10:10:11 +0900 [info]: adding source type="cloudwatch_logs"
1552015-12-15 10:10:11 +0900 [info]: adding match pattern="test.cloudwatch_logs.in" type="file"
1562015-12-15 10:10:11 +0900 [info]: listening fluent socket on 0.0.0.0:24224
157～～～～～
158※td-agent を実行した場合のps
159root      2040  1498  2 13:13 pts/0    00:00:00 /usr/lib64/fluent/ruby/bin/ruby /usr/sbin/td-agent
160root      2042  2040  1 13:13 pts/0    00:00:00 /usr/lib64/fluent/ruby/bin/ruby /usr/sbin/td-agent
161
162※/etc/init.d/td-agent start を実行した場合のps
163td-agent  5531     1  0 09:44 ?        00:00:00 /usr/lib64/fluent/ruby/bin/ruby /usr/sbin/td-agent --group td-agent --log /var/log/td-agent/td-agent.log --daemon /var/run/td-agent/td-agent.pid
164td-agent  5534  5531  0 09:44 ?        00:00:00 /usr/lib64/fluent/ruby/bin/ruby /usr/sbin/td-agent --group td-agent --log /var/log/td-agent/td-agent.log --daemon /var/run/td-agent/td-agent.pid
165