IE 7,8 +Unexpected call to method or property access

This is few scenarios causing above error: 1. Using Jquery append to input

 
$('.btnExample').append("Some html");

2. Setting hiddenField value

 
 $("#hdfSelectedTreeAccount").text(node.get_value());

instead of val() method What's strange in other browser it works fine !@@@

3. http://forum.jquery.com/topic/unexpected-call-to-method-or-property-access-in-ie8