Put data to Web API dosent work in ionic / angularjs

I wrote simple angularJs app for store data in Web api / entity framework. its fine and work very well. but when i want use Ionic for that purpose, i get an error while editing a record.

this is my Controller action:

public IHttpActionResult PutTblLocation(long id, TblLocation tbllocation)
{
    if (!ModelState.IsValid)
    {
        return BadRequest(ModelState);
    }

    if (id != tbllocation.LocationId)
    {
        return BadRequest();
    }

    db.Entry(tbllocation).State = EntityState.Modified;

    try
    {
        db.SaveChanges();
    }
    catch (DbUpdateConcurrencyException)
    {
        if (!TblLocationExists(id))
        {
            return NotFound();
        }
        else
        {
            throw;
        }
    }

    return StatusCode(HttpStatusCode.NoContent);
}

this is my Ionic controller for edit :

   $scope.update = function (location) {
    var obj = {
        LocationId: $stateParams.LocationId,
        LocationName: location.LocationName,
        LocationDescription: location.LocationDescription
    };
    $http.put(ServerPath + "/" + $stateParams.LocationId, $stateParams.LocationId, obj).success(function (data) {
        $state.go('tab.home');
    }).error(function (data) {
        $scope.error = "An Error has occured while updating! " + data;
    });

};

i tried var json = JSON.stringify(obj) but nothing changed…

this is the error:

PUT url/api/locations/15 400 (Bad Request)

its seems has an error with that object i will send. I’d like to say, i have no error with get,add,delete operations. and even i have no any error with all operations in pure angularJS app
thanks