Getting 400 Bad Request from server side

Summary:

I am trying to apply cash advance using REST API, but I am getting 400 Bad Request from the server. Is there anything I am missing from my end

Content (required):

The Request I am sending for ApplyCashAdvance is

POST https://xyz.oraclepdemos.com/fscmRestApi/resources/latest/expenseReports/XXXXX/action/applyCashAdvances HTTP/1.1

Authorization: Basic XXXXX

Accept-Encoding: gzip, deflate

User-Agent: CData Data Provider Engine

Content-Type: application/vnd.oracle.adf.action+json

Content-Length: 46

REST-Framework-Version: 9

 

{

 "cashAdvanceNumber": "ADV000260XXXXXX"

}

Following is the response:

HTTP/1.1 400 Bad Request

Content-Type: application/vnd.oracle.adf.error+json

Content-Length: 520

Referrer-Policy: origin

X-Content-Type-Options: nosniff

Cache-Control: no-cache, no-store, must-revalidate

Location: 

X-ORACLE-DMS-ECID: 005yqKXdnwb5Uc1LJuh8if0007nI0000dS