{Microsoft.WindowsAzure.MobileServices.MobileServiceInvalidOperationException: The request could not be completed.  (Method Not Allowed)

[MobileAppController]
[RoutePrefix("api/register")]
[AllowAnonymous]
public class RegisterController : ApiController
{

     [HttpPost]
    [Route("newuser")]
    public HttpResponseMessage NewUser(RegistrationRequest request)
    {
        // Registration code in here

    }

}

public async Task<Result<UserProfile>> RegisterUser(RegistrationWrapper registrationrequest)
    {
        try
        {
            var registrationRequest = new JObject();
            registrationRequest.Add("username", registrationrequest.username);
            registrationRequest.Add("password", registrationrequest.password);
            registrationRequest.Add("email", registrationrequest.email);
            registrationRequest.Add("phone", registrationrequest.phone);
            registrationRequest.Add("firstname", registrationrequest.firstname);
            registrationRequest.Add("lastname", registrationrequest.lastname);

            var result = await client.InvokeApiAsync("register/newuser", registrationRequest);


     // Handle result here

        }
        catch (Exception ex)
        {
            return Result<UserProfile>.Failure(ex.Message + ex.StackTrace + ex.InnerException);
        }

    }

[MobileAppController]
[RoutePrefix("api/auth")]
public class AuthController : ApiController
{
    public HttpResponseMessage Post(AuthenticationRequest credentials)
    {
        try
        {
              //Authentication code goes here

          catch (Exception e)
        {
            Console.WriteLine("Ërror :" + e.Message);
            Console.WriteLine(e.StackTrace);
            return Request.CreateResponse(HttpStatusCode.InternalServerError, new
            {
                Stacktrace = e.StackTrace,
                ErrorMessage = e.Message,
                Credentials = credentials
            });
        }


    }

async Task<Result<Account>> Login(string username, string password)
    {
        try
        {
            var credentials = new JObject();
            credentials.Add("username", username);
            credentials.Add("password", password);
            var result = await client.InvokeApiAsync("auth", credentials);


          //Handle result here

        }
        catch (Exception ex)
        {
            return Result<Account>.Failure(ex, ex.Message + ex.StackTrace);
        }

    }

}