gb28181中媒体控制功能出现状态码400，由哪些因素可以导致出现此问题

Question

gb28181中对媒体控制<停止遥控>功能抓包，发现最后返回状态码400(请求失败)，一般是由什么原因导致的？SIP协议用c/c++写的，感谢诸君
设备控制流程图如下

MESSAGE sip:37030000001320000023@192.168.44.108:5060 SIP/2.0
Via: SIP/2.0/UDP 192.168.7.173:5060;rport;branch=z9hG4bK2481962925
From: <sip:34020000002000000001@192.168.44.10:5060>;tag=566906519
To: <sip:37030000001320000023@192.168.44.108:5060>
Call-ID: 87951472
CSeq: 20 MESSAGE
Content-Type: application/MANSCDP+xml
Max-Forwards: 70
User-Agent: eXosip/4.0.0
Date: 2022-08-20T10:30:06.947
Content-Length:   172

<?xml version="1.0"?>
<Control>
<CmdType>DeviceControl</CmdType>
<SN>232</SN>
<DeviceID>37030000001320000023</DeviceID>
<PTZCmd>A50F0000000000B4</PTZCmd>
</Control>
SIP/2.0 200 OK
Via: SIP/2.0/UDP 192.168.7.173:5060;rport=5060;branch=z9hG4bK2481962925;received=192.168.44.10
From: <sip:34020000002000000001@192.168.44.10:5060>;tag=566906519
To: <sip:37030000001320000023@192.168.44.108:5060>;tag=1877995810
Call-ID: 87951472
CSeq: 20 MESSAGE
User-Agent: Sent IC6
Content-Length: 0

MESSAGE sip:34020000002000000001@192.168.44.10:5060 SIP/2.0
Via: SIP/2.0/UDP 192.168.44.108:5060;rport;branch=z9hG4bK649764036
From: <sip:37030000001320000023@192.168.44.10:5060>;tag=160158174
To: <sip:34020000002000000001@192.168.44.10:5060>
Call-ID: 1056972173
CSeq: 20 MESSAGE
Content-Type: Application/MANSCDP+xml
Max-Forwards: 70
User-Agent: Sent IC6
Content-Length:   153

<?xml version="1.0"?>
<Response>
<CmdType>DeviceControl</CmdType>
<SN>232</SN>
<DeviceID>37030000001320000023</DeviceID>
<Result>OK</Result>
</Response>
SIP/2.0 400 Bad Request                      //这里出现了状态码400，是由于哪些原因可能导致此事件发生
Via: SIP/2.0/UDP 192.168.44.108:5060;rport=5060;branch=z9hG4bK649764036
From: <sip:37030000001320000023@192.168.44.10:5060>;tag=160158174
To: <sip:34020000002000000001@192.168.44.10:5060>;tag=957540208
Call-ID: 1056972173
CSeq: 20 MESSAGE
User-Agent: eXosip/4.0.0
Content-Length: 0