I have build a page to insert district name but on inserting if a field is blank then its not displaying any message.

Below is my code:

@model ROMvcApplication.Models.districtModelClass

@{
    ViewBag.Title = "Index";
    Layout = "~/Views/Shared/_DashboardAdminLayout.cshtml";
}

<!-- Display Section -->
<!-- Begin Page Content -->
    <div class="container-fluid">

       <!-- Page Heading -->
       <h1 class="h3 mb-4 text-gray-800">Add/Modify District</h1>

    </div>
<!-- /.container-fluid -->
@using (@Html.BeginForm())
{
    @Html.AntiForgeryToken()
    @Html.ValidationSummary(true, "", new { @class = "text-danger" })
<div ng-app="MyApp" ng-controller="MyController">
    <table width="100%" border="0">
        <tr>
            <td align="center" valign="top">
                <table border="0" cellpadding="0" cellspacing="0" width="600">
                    <tr>
                        <td style="width: 150px">District Name<br />
                            <input type="text" ng-model="district_Name" style="width: 140px"/>
                            @Html.ValidationMessageFor(model => model.districtname, "", new { @class = "text-danger" })
                        </td>
                        <td style="width: 200px">
                            <br />
                            <input type="button" value="Add" ng-click="Add()" />
                        </td>
                    </tr>
                </table>
            </td>
        </tr>
        <tr>
            <td align="center" valign="top">
                <table id="tblCustomers" class="table" cellpadding="0" cellspacing="0" width="600">
                    <tr>
                        <th style="width: 100px">District Id
                        </th>
                        <th style="width: 150px">District
                        </th>
                        <th style="width: 100px"></th>
                    </tr>
                    <tbody ng-repeat="m in districtModelClass">
                        <tr>
                            <td>
                                <span>{{m.districtid}}</span>
                            </td>
                            <td>
                                <span ng-hide="m.EditMode">{{m.districtname}}</span>
                                <input type="text" ng-model="m.districtname" ng-show="m.EditMode" />
                            </td>
                            <td>
                                <a class="Edit" href="javascript:;" ng-hide="m.EditMode" ng-click="Edit($index)">Edit</a>
                                <a class="Update" href="javascript:;" ng-show="m.EditMode" ng-click="Update($index)">Update</a>
                                <a class="Cancel" href="javascript:;" ng-show="m.EditMode" ng-click="Cancel($index)">Cancel</a>
                                <a href="javascript:;" ng-hide="m.EditMode" ng-click="Delete(m.districtid)">Delete</a>
                            </td>
                        </tr>
                    </tbody>
                </table>
            </td>
        </tr>
    </table>
</div>
}
<!-- Ends Here -->

Models -> districtModelClass:

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Web;

namespace ROMvcApplication.Models
{
    public class districtModelClass
    {
        [Key]
        public Int32 districtid { get; set; }
        [Required(ErrorMessage="Enter district name")]
        public string districtname { get; set; }
    }
}