HttpDelete - Method Not Allowed - Only Get,Post and Put.

Dear friends,

First of all, I'm sorry if this question has already been solved and I could not find it in the forums.

I'm having a strange problem in my WebApi2. I have a fully functioning Get, Post and Put methods. However, I don't know why the Delete method is giving 405 - Method Not Allowed error.

The methods have the same built structure and authorization, so I believe this is due to a IIS configuration situation.

Here is the error:

Here is the WebApi2 code:

[HttpDelete]
        [Route("")]
        public bool Delete(string userId)
        {
            ThreeLayerDemo.Logic.BUS.UserBUS objOperations = new ThreeLayerDemo.Logic.BUS.UserBUS();
            bool deleteResult = objOperations.Delete(userId);
            return deleteResult;
        }

Here is the client consuming code:

DialogResult dR = MessageBox.Show("Delete?", "Delete?", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2);
            if (dR == System.Windows.Forms.DialogResult.Yes)
            {
                string idCliente = gridClientes.Rows[gridClientes.SelectedRows[0].Index].Cells[0].Value.ToString();

                HttpClientHandler handler = new HttpClientHandler();
                handler.Credentials = new NetworkCredential("tiago", "???");

                using (var client = new HttpClient(handler))
                {
                    client.Timeout = TimeSpan.FromSeconds(500);
                    var jsonVariable = new JavaScriptSerializer().Serialize(idCliente);

                    System.Threading.Tasks.Task<HttpResponseMessage> responseTask;
                    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
                    HttpRequestMessage req = new HttpRequestMessage(HttpMethod.Delete, "http://dataServices.????.com/api/clientes");
                    //req.Content = new StringContent(jsonVariable, Encoding.UTF8, "application/json");
                    req.Content = new StringContent(idCliente);

                    responseTask = client.SendAsync(req);
                    responseTask.Wait();
                    MessageBox.Show(responseTask.Result.ToString());
                }
            }

Thank you for your help in advance.