Response status code does not indicate success: '400' ('Bad request') - asp.net-web-api

Question

i want to POST data to API in my android xamarin app using refit i've tested the API at Postman and it's working fine but at android app i'm getting exception Bad request.
Here is my android code i added the interface and the model i don't know what is the problem .
public interface RequestAPI
{
[Post("/request")]
Task<create_request> submit([Body] create_request request);
}
requestAPI= RestService.For<RequestAPI>("http://courier-magconsulting.azurewebsites.net/api");
button.Click += async delegate
{
try
{
create_request request = new create_request();
request.PickUpPhone = "7664554";
request.DownPayment = 89;
request.DeliveryFees = 56.8;
request.Note = "i need a help!";
request.RequestID = 88; // replace the value yourself
request.DekiveryLocationLatitude = 2323;
request.DeliveryLocationLongitude = 232;
request.PickUpLocationLatitude = 898;
request.PickUpLocationLongitude = 1123;
BroadcastType type = new BroadcastType();
type.Name = "All";
type.ID = 60; // replace the value yourself
request.BroadcastType = type;
Cargosize size = new Cargosize();
size.Name = "Small";
size.ID = 1; // replace the value yourself
request.Cargosize = size;
Cargoweight weight = new Cargoweight();
weight.Name = "Large";
weight.ID = 2; // replace the value yourself
request.CargoWeight = weight;
Sender sender_ = new Sender();
sender_.Name = "Ahmad";
sender_.SenderID = 1; // replace the value yourself
sender_.Phone = "8788";
sender_.SocialID = "8787";
sender_.RatingAvg = 5;
SenderStatus status = new SenderStatus();
status.ID = 1;
status.Name = "Active";
sender_.Senderstatus = status;
request.Sender = sender_;
create_request result = await requestAPI.submit(request);
Toast.MakeText(this, "Request created", ToastLength.Long).Show();
}
catch(Exception ex)
{
Toast.MakeText(this, ex.Message, ToastLength.Long).Show();
}
};