title: how to create wordpress admin menu and link to page
body: <p><strong>I want to create a plugin</strong> i got error : <strong>You do not have sufficient permissions to access this page</strong>. there are 2 file 
  buffer.php 
  bufferpage.php</p>
  
  <p>i already create admin menu but i want to display/show  "bufferpage.php" <strong>in right side after click submenu named Submenu-3</strong></p>
  
  <p>but notworking :(</p>
  
  <p>buffer.php <strong>is here</strong></p>
  
  <pre><code>//Register the main menu name “buffercode_menu”
  add_action( 'admin_menu', 'buffercode_menu');
  
  
      //adding menu menu in wordpress admin panel
      function buffercode_menu() {
  
      add_menu_page( 'BufferCode plugin page', 'Menu plugin settings','manage_options', __FILE__,'buffercode_plugin',plugins_url( '/images/menu-icon.png', __FILE__ ) );
  
      //submenu
      add_submenu_page( __FILE__, 'BufferCode Submenu','Submenu-1', 'manage_options',__FILE__.'_menu1', buffercode_plugin );
      add_submenu_page( __FILE__, 'BufferCode Submenu','Submenu-2', 'manage_options',__FILE__.'_menu1', buffercode_plugin );
      add_submenu_page( __FILE__, 'BufferCode Submenu','Submenu-3', 'manage_options',__FILE__. $view_level, 'bufferpage.php' );
      }
  </code></pre>
  
  <p>here is bufferpage.php</p>
  
  <pre><code>&lt;div class="wrap"&gt;
      &lt;?php echo "&lt;h2&gt;" . __( 'Sample page', 'buffercode_menu' ) . "&lt;/h2&gt;"; ?&gt;
  
  &lt;?php
  
  global $wpdb;
  /* wpdb class should not be called directly.global $wpdb variable is an instantiation of the class already set up to talk to the WordPress database */ 
  
  $result = $wpdb-&gt;get_results( "SELECT * FROM wp_savans "); /*mulitple row results can be pulled from the database with get_results function and outputs an object which is stored in $result */
  
  //echo "&lt;pre&gt;"; print_r($result); echo "&lt;/pre&gt;";
  /* If you require you may print and view the contents of $result object */
  
  ?&gt;
  &lt;table width="100%" border="1"&gt;
    &lt;tr&gt;
      &lt;td width="116" align="center" bgcolor="#FFFF99"&gt;&lt;strong&gt;Name&lt;/strong&gt;&lt;/td&gt;
      &lt;td width="146" align="center" bgcolor="#FFFF99"&gt;&lt;strong&gt;Email&lt;/strong&gt;&lt;/td&gt;
    &lt;/tr&gt;
  &lt;?php
  foreach($result as $row)
   {
  echo "&lt;tr align=center&gt;
      &lt;td&gt;$row-&gt;name&lt;/td&gt;
      &lt;td&gt;$row-&gt;email&lt;/td&gt;
    &lt;/tr&gt;";
   }
   /* Print the contents of $result looping through each row returned in the result */
  
  ?&gt;
  &lt;/table&gt;
  &lt;/div&gt;
  </code></pre>