Upload File Unsuccessful, using Net Core 2.0

Hi,

Trying to upload file unsuccessfull. Any one can help me please? I am using Net.Core 2.0
Here my model UploadFile.cs:

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Http.Internal;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace PalipiInnovation.Entities
{
    public class UploadFile
    {
        public int Id { get; set; }

        [Required, StringLength(100)]
        public string Name { get; set; }

        [Display(Name = "File Path")]
        public string FilePath { get; set; }

        [Display(Name = "Thumbnail Path")]
        public string ThumbNailPath { get; set; }

        [Display(Name = "Url")]
        public string UrlPath { get; set; }

        [Required]
        [NotMapped]
        [Display(Name = "Document File")]
        public FormFile DocumentFile { get; set; }
    }
}

Here my Create Action:

        public IActionResult Create()
        {
            return View();
        }

        [HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> Create([Bind("Id,Name,FilePath,ThumbNailPath,UrlPath,DocumentFile")] UploadFile uploadFile)
        {
            if (ModelState.IsValid)
            {
                uploadFile.FilePath = uploadFile.DocumentFile.FileName;
                await UploadDocument();
                _context.Add(uploadFile);
                await _context.SaveChangesAsync();
                Message = $"Upload document {UploadFile.FilePath} has been successfully!";

                return RedirectToAction(nameof(Index));
            }
            return View(uploadFile);
        }

Here my View Create.cshtml:

@model PalipiInnovation.Entities.UploadFile
@{
    ViewData["Title"] = "Create";
}<div class="panel panel-default container" style="margin-top:25px;"><div class="panel-heading panel-title">@ViewData["Title"]</div><div class="panel-body"><div class="row"><div class="col-md-4"><form method="post" asp-action="Create" enctype="multipart/form-data"><div asp-validation-summary="ModelOnly" class="text-danger"></div><div class="form-group-sm"><label asp-for="Name" class="control-label"></label><input asp-for="Name" class="form-control" /><span asp-validation-for="Name" class="text-danger"></span></div><div class="form-group-sm"><label asp-for="DocumentFile" class="col-md-3 control-label"></label><div class="col-md-9"><input asp-for="DocumentFile" type="file" class="form-control" style="height:auto" /><span asp-validation-for="DocumentFile" class="text-danger"></span></div></div><div class="form-group-sm col-md-offset-3"><input type="submit" value="Create" class="btn btn-success" style="margin-top:15px" /></div></form><a asp-action="Index" class="btn btn-primary col-md-offset-3">Back to List</a></div></div></div></div>
@section Scripts {
    @{await Html.RenderPartialAsync("_ValidationScriptsPartial");}
}

Thanks guys
Jannen Siahaan