Bad Request error setting header in Ebay API

I was able to fix the issue by not converting the request to json but send as object. Though the error provided is very generic and could not identify the main issue. Upon asking to someone has experienced in ebay integration, the main issue is to provide all the needed in the headers.

 public HttpResponseMessage PostHttpResponse(string requestUri, object data)
{
    using (var client = CreateHttpClient())
    {
        try
        {
            HttpResponseMessage response = client.PostAsJsonAsync(requestUri, data).Result;
            if (response.IsSuccessStatusCode)
            {
                return response;
            }
            else
            {
                GetErrorsResponse(response);
                throw new HttpRequestException(string.Format("There was an exception trying to post a request. response: {0}", response.ReasonPhrase));
            }
        }
        catch (HttpRequestException ex)
        {
            throw ex;
            //return null;
        }
    }
}

And in the httpclient needs to add the header.

private HttpClient CreateHttpClient()
        {
            var client = new HttpClient();
            ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;

            string baseAddress = WebApiBaseAddress;
            if (string.IsNullOrEmpty(baseAddress))
            {
                throw new HttpRequestException("There is no base address specified in the configuration file.");
            }
            client.Timeout = new TimeSpan(0, 5, 59);
            client.BaseAddress = new Uri(baseAddress);
            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Add("Authorization", string.Format("Bearer {0}", _cred.eBayToken));
            client.DefaultRequestHeaders.Add("Accept-Language", "en-US");
            client.DefaultRequestHeaders.Add("Accept-Charset", "utf-8");
            client.DefaultRequestHeaders.Add("Accept", "application/json");
            client.DefaultRequestHeaders.Add("LegacyUse", "true");
            return client;
        }