TypeScript call API Error ODP_DESERIALIZATION_ERROR

Hello, my first week dealing with ifs
I am trying to automate work flow. it creates work order when I try it with postman  but when I try to do it pragmatically It shows error in Application messages in ifs UI

I am using following 

Header

{ "Content-Type" : "application/json", 

"Authorization" : "Bearer ACCESS_TOKEN" 

}

url: https://my_company.ifs.cloud/

endpoint: /int/soapgateway

and I am sending my json as body for creating a work order

I

 IT gives Following Error in Application messages on UI 
ODP_DESERIALIZATION_ERROR Error while de-serializing contents.

Any Help would be appreciated