IE exec command rich text editing

I'm tring to insert an image in a WYSIWYG editor, but I can't insert images in Internet Explorer(6/7), although it works fine within Firefox. It fails without throwing any errors.

This is what I'm using:

execCommand('insertImage', false, 'absolute/path/to/an/image');

From stackoverflow

• In IE, execCommand exists on the document object, not the window object. (Well, it also exists on range objects, too, but anyway.)

  Try:

  document.execCommand("insertImage", false, "absolute/path/to/an/image");
  

• Thanks for the answer, but as it turned out my problem appeared because IE couldn't insert the image if my iframe (the richeditor container) didn't have focus. So I used the following code just before trying to use execCommand and it worked.

  document.getElementById('iframeId').contentWindow.focus();