Using RestSharp I ever see "{\"message\": \"TypeError: sign() takes at least 2 arguments (0 given)\", \"exception\": \"TypeError\"}"

Question

I using RestSharp (v 107.3.0.0) to post data on a Web API, when I using postman to test te post is ok, bu when I using RestSharp ever I receive: "{"message": "TypeError: sign() takes at least 2 arguments (0 given)", "exception": "TypeError"}"

Resumin my code:

var client = new RestClient(http://192.168.2.59);
var request = new RestRequest("api/sign", Method.Post);

/* here I set some AddParameter, but using parameter or not I ever seen the same error. For that reason I will not put these parementer and too proteted some sensitive proyect information. */

RestResponse response = await client.PostAsync(request);

The error will to be clear, but sing is not a method, is a resource.