fnIsOpen is not working

Here is my code
$('#tblsamplebody ').on('click', 'img', function () {
var nTr = $(this).parents('tr')[0];
var nTds = this;
if (dTable.fnIsOpen(nTr)) {
/* This row is already open - close it */
this.src = "http://i.imgur.com/SD7Dz.png";
dTable.fnClose(nTr);
}
}

Usind DT1.10.7
DT tabletools 2.2.4