ExtJS-Clone Checkboxes and adding them dynamically

JavaScript
1

cloneNode method is giving me the following errors–>
oldCheckBox.cloneNode is not a function


handler: function() {	
var oldCheckBox = newContactsPanel.items.items;
var newCheckBox = oldCheckBox.cloneNode(true);					
newContactsPanel.items.items.appendChild(newCheckBox);	
}

then I tried the appendChild () and was getting the following errors–>

Node cannot be inserted at the specified point in the hierarchy" code: "3


var newCheckBox = document.createElement('input');
newCheckBox.type = "checkbox";
var oldCheckBox = newContactsPanel.items.items;
newCheckBox.appendChild(oldCheckBox);
document.getElementById('input').appendChild(newCheckBox);
return false;

any enlightenment into my ‘end of a Monday’ blues would be much appreciated…
thanks.