title: add row dynamically to existing jsonstore gridpanel extjs
body: <p>I have created a gridpanel with JsonStore. I am trying to add new row to the existing store in my gridpanel. I am able to add the row but it is showing some error like </p>
  
  <p>"<strong>Uncaught TypeError: Cannot call method 'addClass' of null</strong> ".</p>
  
  <p>My code to add new row is ,</p>
  
  <pre><code>var rec = {};
  rec["id"] = "1";
  rec["name"] = "kk";
  var dataStore = Ext.getCmp('myGridPanel').getStore();
  var myNewRecord = new dataStore.recordType(rec);
  dataStore.add(myNewRecord);
  </code></pre>
  
  <p>Help me in this.</p>
  
  <p>Thanks in advance.</p>