why fnCellRender doesn't work in my project

Hello,I try to use fnCellRender even example from your api doesn't work
from https://datatables.net/extensions/tabletools/button_options

"fnCellRender": function ( sValue, iColumn, nTr, iDataIndex ) { // Append the text 'TableTools' to column 5 if ( iColumn === 5 ) { return sValue +" TableTools"; } return sValue; }

Thanks a lot