kalpesh says:
$('[id*=gvSource]').find("tbody").append("<tr>" + ui.item.html() + "</tr>");
You need to replace the above line with the below line.
$("<tr>" + ui.item.html() + "</tr>").insertAfter($('[id*=gvSource]').find("tbody").find('tr').eq($(ui.item).index() - 1));
I have updated the sample code. Please check.