Cannot set authorization header in c#

I'm trying to setting my Jwt token in C# code.

 [HttpPost]
    public IActionResult TestPOST ()
    {
        var token = "myExampleJwtTokenNormallyIGrabItFromOtherFunction";
        var client = new HttpClient();
        client.DefaultRequestHeaders.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", token);
        return Ok();
    }

This method just return Ok(), but Authorization is not setting. And I still have 401 http error. I cannot figured out what can be wrong here. I read that should I use

client.DefaultRequestHeaders.TryAddWithoutValidation("Authorization", "Bearer " + token);

but it still does not work. How should I set header? Have anyone any idea?