ASP.NET IIS10 service.svc error 406 not acceptable

Hi there, 

i have a service .svc hosted on a machine whit windows server 2019 on IIS 10, im tryng to send a POST request whit postman sending a json whit the following headers:

Postman-Token:  calculated when request is sent>

Content-Lenght: calculated when request is sent

Host:           calculated when request is sent

Accept:         * / *

Content-Type:   application/json

and this in the body:

{   "orderNumber": "12345",     "idTransaction":"1",     "authorization":"auth",     "amount":"14.95",     "paymentDate":"2020-01-01",     "currency":"euro",     "resultCode": "ok" }

the service responds correctly and read the json but the status is "406 Not Accettable" ,

as you can see i have placed the Accept header whit value "* / *" that mean accept every kind of content-type in the response,

and that is the response that i get:

response headers:

Content-Type:   application/json; charset=utf-8

Server:         Microsoft-IIS/10.0

X-Powered-By:   ASP.NET

Date:           Mon, 04 Jan 2021 09:54:27 GMT

Content-Length: 69

response body

"Not found any payment whit numeroOrdine=12345."

the server/service read the json and respond corretly couse the number of order 12345 was an example and dosent exist,

but whit status code 406 not accetable,

i tryed also to add the header Accept-Charset: UTF-8 in the request but the situation dosent change,

i checked on iis on the server and after select on the mime type list i can that application/json is in the list, 

maybe i have to enable it somewhere else? Specify the mime type in the web.config file?

or it could be something else?

thanks in advance