zabbixのactivecheckに失敗する

##現象
ZabbixAgentのPassiveCheckには成功するが、ActiveCheckに失敗してしまいます。
ログの出力状況をみると、通信はできているが送られてきたデータの処理でエラーが出ているようです。
よろしくお願いいたします。

##環境
OS：Ubuntu18.04
ZabbixServer：4.0.16
Zabbix Agent：4.4.2

ZabbixServerの入った端末とZabbixAgentの入った端末は同一LAN内に存在します。
Server（192.168.188.232）
Agent（192.168.188.209）

##ログ

zabbix_agent2.log
1
22019/12/20 10:22:44.033748 [1] In refreshActiveChecks() from [192.168.188.232:10051]
32019/12/20 10:22:44.033997 connecting to [192.168.188.232:10051]
42019/12/20 10:22:44.035036 sending [{"request":"active checks","host":"net","version":"4.4","ip":"192.168.188.209"}] to [192.168.188.232:10051]
52019/12/20 10:22:44.036024 receiving data from [192.168.188.232:10051]
62019/12/20 10:22:44.039737 received [{"response":"success","data":[{"key":"agent.hostname","delay":60,"lastlogsize":0,"mtime":0}]}] from [192.168.188.232:10051]
72019/12/20 10:22:44.040232 [1] cannot parse list of active checks from [192.168.188.232:10051]: json: cannot unmarshal number into Go struct field Request.data.delay of type string
82019/12/20 10:22:44.040284 [1] End of refreshActiveChecks() from [192.168.188.232:10051]

##設定ファイル

zabbix_agent2.conf
1# This is a configuration file for Zabbix agent 2 (Unix)
2# To get more information about Zabbix, visit http://www.zabbix.com
3
4############ GENERAL PARAMETERS #################
5
6### Option: PidFile
7#	Name of PID file.
8#
9# Mandatory: no
10# Default:
11# PidFile=/tmp/zabbix_agent2.pid
12
13PidFile=/var/run/zabbix/zabbix_agent2.pid
14
15### Option: LogType
16#	Specifies where log messages are written to:
17#		system  - syslog
18#		file    - file specified with LogFile parameter
19#		console - standard output
20#
21# Mandatory: no
22# Default:
23# LogType=file
24
25### Option: LogFile
26#	Log file name for LogType 'file' parameter.
27#
28# Mandatory: yes, if LogType is set to file, otherwise no
29# Default:
30# LogFile=
31
32LogFile=/var/log/zabbix/zabbix_agent2.log
33
34### Option: LogFileSize
35#	Maximum size of log file in MB.
36#	0 - disable automatic log rotation.
37#
38# Mandatory: no
39# Range: 0-1024
40# Default:
41# LogFileSize=1
42
43LogFileSize=0
44
45### Option: DebugLevel
46#	Specifies debug level:
47#	0 - basic information about starting and stopping of Zabbix processes
48#	1 - critical information
49#	2 - error information
50#	3 - warnings
51#	4 - for debugging (produces lots of information)
52#	5 - extended debugging (produces even more information)
53#
54# Mandatory: no
55# Range: 0-5
56# Default:
57# DebugLevel=3
58DebugLevel=5
59
60### Option: SourceIP
61#	Source IP address for outgoing connections.
62#
63# Mandatory: no
64# Default:
65# SourceIP=
66
67##### Passive checks related
68
69### Option: Server
70#	List of comma delimited IP addresses, optionally in CIDR notation, or DNS names of Zabbix servers and Zabbix proxies.
71#	Incoming connections will be accepted only from the hosts listed here.
72#	If IPv6 support is enabled then '127.0.0.1', '::127.0.0.1', '::ffff:127.0.0.1' are treated equally
73#	and '::/0' will allow any IPv4 or IPv6 address.
74#	'0.0.0.0/0' can be used to allow any IPv4 address.
75#	Example: Server=127.0.0.1,192.168.1.0/24,::1,2001:db8::/32,zabbix.example.com
76#
77# Mandatory: yes, if StartAgents is not explicitly set to 0
78# Default:
79# Server=
80Server=192.168.188.232
81
82### Option: ListenPort
83#	Agent will listen on this port for connections from the server.
84#
85# Mandatory: no
86# Range: 1024-32767
87# Default:
88# ListenPort=10050
89
90### Option: ListenIP
91#	List of comma delimited IP addresses that the agent should listen on.
92#	First IP address is sent to Zabbix server if connecting to it to retrieve list of active checks.
93#
94# Mandatory: no
95# Default:
96# ListenIP=0.0.0.0
97ListenIP=192.168.188.209
98
99### Option: StatusPort
100#	Agent will listen on this port for HTTP status requests.
101#
102# Mandatory: no
103# Range: 1024-32767
104# Default:
105# StatusPort=
106
107##### Active checks related
108
109### Option: ServerActive
110#	List of comma delimited IP:port (or DNS name:port) pairs of Zabbix servers and Zabbix proxies for active checks.
111#	If port is not specified, default port is used.
112#	IPv6 addresses must be enclosed in square brackets if port for that host is specified.
113#	If port is not specified, square brackets for IPv6 addresses are optional.
114#	If this parameter is not specified, active checks are disabled.
115#	Example: ServerActive=127.0.0.1:20051,zabbix.domain,[::1]:30051,::1,[12fc::1]
116#
117# Mandatory: no
118# Default:
119# ServerActive=
120ServerActive=192.168.188.232:10051
121
122### Option: Hostname
123#	Unique, case sensitive hostname.
124#	Required for active checks and must match hostname as configured on the server.
125#	Value is acquired from HostnameItem if undefined.
126#
127# Mandatory: no
128# Default:
129# Hostname=
130
131Hostname=net
132
133### Option: HostnameItem
134#	Item used for generating Hostname if it is undefined. Ignored if Hostname is defined.
135#	Does not support UserParameters or aliases.
136#
137# Mandatory: no
138# Default:
139# HostnameItem=system.hostname
140
141### Option: HostMetadata
142#	Optional parameter that defines host metadata.
143#	Host metadata is used at host auto-registration process.
144#	An agent will issue an error and not start if the value is over limit of 255 characters.
145#	If not defined, value will be acquired from HostMetadataItem.
146#
147# Mandatory: no
148# Range: 0-255 characters
149# Default:
150# HostMetadata=
151
152### Option: HostMetadataItem
153#	Optional parameter that defines an item used for getting host metadata.
154#	Host metadata is used at host auto-registration process.
155#	During an auto-registration request an agent will log a warning message if
156#	the value returned by specified item is over limit of 255 characters.
157#	This option is only used when HostMetadata is not defined.
158#
159# Mandatory: no
160# Default:
161# HostMetadataItem=
162
163### Option: RefreshActiveChecks
164#	How often list of active checks is refreshed, in seconds.
165#
166# Mandatory: no
167# Range: 60-3600
168# Default:
169# RefreshActiveChecks=120
170
171### Option: BufferSend
172#	Do not keep data longer than N seconds in buffer.
173#
174# Mandatory: no
175# Range: 1-3600
176# Default:
177# BufferSend=5
178
179### Option: BufferSize
180#	Maximum number of values in a memory buffer. The agent will send
181#	all collected data to Zabbix Server or Proxy if the buffer is full.
182#
183# Mandatory: no
184# Range: 2-65535
185# Default:
186# BufferSize=100
187
188############ ADVANCED PARAMETERS #################
189
190### Option: Alias
191#	Sets an alias for an item key. It can be used to substitute long and complex item key with a smaller and simpler one.
192#	Multiple Alias parameters may be present. Multiple parameters with the same Alias key are not allowed.
193#	Different Alias keys may reference the same item key.
194#	For example, to retrieve the ID of user 'zabbix':
195#	Alias=zabbix.userid:vfs.file.regexp[/etc/passwd,^zabbix:.:([0-9]+),,,,\1]
196#	Now shorthand key zabbix.userid may be used to retrieve data.
197#	Aliases can be used in HostMetadataItem but not in HostnameItem parameters.
198#
199# Mandatory: no
200# Range:
201# Default:
202
203### Option: Timeout
204#	Spend no more than Timeout seconds on processing
205#
206# Mandatory: no
207# Range: 1-30
208# Default:
209# Timeout=3
210
211### Option: Include
212#	You may include individual files or all files in a directory in the configuration file.
213#	Installing Zabbix will create include directory in /usr/local/etc, unless modified during the compile time.
214#
215# Mandatory: no
216# Default:
217# Include=
218
219Include=/etc/zabbix/zabbix_agent2.d/*.conf

##Zabbixのアイテム
名前　hostname
タイプ　Zabbixエージェント（アクティブ）
キー　agent.hostname
データ型　ログ
監視間隔　1m
ヒストリの保存期間　Storage period　90d
ログの時間の形式
アプリケーションの作成
アプリケーション　-なし-
説明