title: Warning: call_user_func_array() expects parameter 1 to be a valid callback, function 'myplguin_admin_page' not found or invalid function name
body: <p>I am adding a new page to wordpress-menu.But it is giving me the error:</p>
  
  <blockquote>
    <p>Warning: call_user_func_array() expects parameter 1 to be a valid callback, function 'myplguin_admin_page' not found or invalid function name.</p>
  </blockquote>
  
  <p>What is that I am missing?</p>
  
  <p><strong>plugin.php</strong></p>
  
  <pre><code>add_action( 'admin_menu', 'my_admin_menu' );
  
  function my_admin_menu() {
      add_menu_page( 'My Top Level Menu Example', 'VENDOR RATE UPDATE LOG', 'administrator', 'tested.php', 'myplguin_admin_page', 'dashicons-tickets', 6  );
  }
  </code></pre>
  
  <p><strong>tested.php</strong></p>
  
  <pre><code>function myplguin_admin_page(){
      ?&gt;
      &lt;div class="wrap"&gt;
          &lt;h2&gt;Welcome To My Plugin&lt;/h2&gt;
      &lt;/div&gt;
      &lt;?php
  }
  </code></pre>