title: ng-disabled is not disabling a button in Angular JS
body: <p>Why does the Button is not disable? </p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>var mainApp = angular.module('mainApp', []);
  
  mainApp.controller('mainController', function ($scope) {
      $scope.form = {
          login: ''
      };
  });</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;form ng-controller="LoginAppCtrl as lc" ng-app="MTApp"&gt;
    &lt;div class="login"&gt;
      &lt;h1&gt;LOG IN&lt;/h1&gt; 
    &lt;/div&gt;
    &lt;div&gt;
      &lt;div&gt;User Name :&lt;/div&gt;
      &lt;div&gt;
        &lt;input type="text" name="tbUserName" required ng-model="lc.request.user"&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  
    &lt;div&gt;
      &lt;div&gt;Password :&lt;/div&gt;
      &lt;div&gt;
        &lt;input type="text" name="tbPassword" required ng-model="lc.request.password"&gt;
      &lt;/div&gt;
    &lt;/div&gt;
    &lt;div&gt;
      &lt;div&gt;
        &lt;button ng-click="lc.submitRequest()" ng-disabled="lc.request.user == '' || lc.request.password == '' "&gt;Sign In&lt;/button&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  &lt;/form&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>I'm new in Angular JS and I am trying to make a simple login form, that if login success will be shown other form, and if not, login form will be stayed.
  Can anyone help me? I need the basic tutorials.</p>