MVC Controller gets NULL Exception - asp.net

Question

I am using ASP.NET Core and AngularJS (not AngularJS 2). I followed this link AngularJS Tutorial for Login with MVC but my mvc controller (AuthenticateUser) gets null value. Though I am getting this value through my script
JSON:
Password: "test"
UserName: "test"
Source:
{"UserName":"test","Password":"test"}
And though I append [FromBody], the controller (AuthenticateUser) still gets null value.
Here is my code:
Service.js
app.service("myAppService", function ($http) {
this.UserLogin = function (User) {
var response = $http({
method: "post",
url: "../Administrator/AuthenticateUser",
data: JSON.stringify(User),
dataType: "json"
});
return response;
}
});
Controller.js
app.controller("MyAppController", function ($scope, MyAppService) {
$scope.LoginCheck = function () {
var User = {
UserName: $scope.usrName,
Password: $scope.usrPassword
};
var getData = MyAppService.UserLogin(User);
getData.then(function (d) {
alert(d.UserName);
});
debugger;
}
});
Index.cshtml
<div class="container">
<div id="loginbox" style="margin-top:50px;" class="mainbox col-md-6 col-md-offset-3 col-sm-8 col-sm-offset-2">
<div class="panel panel-info">
<div class="panel-heading">
<div class="panel-title">Sign In</div>
<div style="float:right; font-size: 80%; position: relative; top:-10px">Forgot password?</div>
</div>
<div style="padding-top:30px" class="panel-body">
<div style="display:none" id="login-alert" class="alert alert-danger col-sm-12"></div>
<form id="loginform" class="form-horizontal" role="form">
<div style="margin-bottom: 25px" class="input-group">
<span class="input-group-addon"><i class="glyphicon glyphicon-user"></i></span>
<input type="text" class="form-control" ng-model="usrName" placeholder="Username">
</div>
<div style="margin-bottom: 25px" class="input-group">
<span class="input-group-addon"><i class="glyphicon glyphicon-lock"></i></span>
<input type="password" class="form-control" ng-model="usrPassword" placeholder="Password">
</div>
<div style="margin-top:10px" class="form-group">
<!-- Button -->
<div class="col-sm-12 controls">
<button type="button" class="btn btn-success" ng-click="LoginCheck();">Login</button>
</div>
</div>
</form>
</div>
</div>
</div>
</div>
AdministratorController.cs
public class AdministratorController : Controller
{
private TestDBOnlineContext _context;
// GET: /<controller>/
public IActionResult Index()
{
return View();
}
[HttpPost]
public JsonResult AuthenticateUser(UserAccessViewModel _users)
//public string AuthenticateUser(UserAccessViewModel userAccess)
{
//string msg = string.Empty;
//if (userAccess.UserName == null || userAccess.UserPassword == null)
// return "Please fill-out all entries";
//else
//{
var users = _context.UserAccess.Where(w => w.Username.Equals(_users.UserName) &&
w.Userpassword.Equals(_users.UserPassword));
// if (users != null)
// return "Thanks for logging.";
// else
// return "Invalid username or password.";
//}
return Json(users);
}
}
Hope that you can help me on this. I stuck for many days already. Thanks in advance.