Text Callout not working

I'm trying to insert Text callout, however its not showing up. It only showing the annotation box without arrow pointer. Please refer the code mentioned below:

var link = "http://www.example.com/";
var spans = new Array();
  spans[0] = new Object();
  spans[0].text = "Links to: ";
  spans[0].textSize = 12;
  spans[0].textColor = color.red;
  spans[1] = new Object();
  spans[1].text = link;
  spans[1].textSize = 12;
  spans[1].textColor = color.black;

var annot = this.addAnnot({ page: 0, type: "FreeText", intent: "FreeTextCallout", rect: [10, 10, 10, 10], richContents: spans });