Added ajax to a Link but its not working
I did it : 
The problem was in my callback function : 

function custom_ajaxcallback($type = 'ajax') {
  if($type == 'ajax') {
    $output = t('Hello World!');
    $command = array();
    $commands[] = ajax_command_append('#sayinghello', $output);
    $page = array('#type' =&gt; 'ajax', '#commands' =&gt; $commands); --&gt; In this line
    ajax_deliver($page);
  }
  else{
    return t("Hello world in new page.");
  }
}