hi, im trying to build my first grid with subgrid, ive checked the demo files, but once i insert this block of code, the grid doesnt even work. i cant understand what is wrong

$opt["subGrid"] = true;
$opt["subgridurl"] = "subgrid.php";
$opt["height"] = "";
$opt["rowNum"] = "5";
$opt["subgridparams"] = "Contrato,cliente"; // no spaces b/w column names
$opt["loadComplete"] = "function(){ var rowid=2; 
									jQuery('tr#'+rowid+' td[aria-describedby$=subgrid]').html(''); 
									jQuery('tr#'+rowid+' td[aria-describedby$=subgrid]').unbind(); 
									 }"; 
$grid->set_options($opt);

If someone could send me an example with the code of subgrid.php it would be awsome to Thank you