[DjSap]

well checked how it worked and found that functions.php should be changed

find this line:
$post[posttime]=vbdate($timeformat,$post[dateline]);

below it add:
$post[lastactivedate]=vbdate($dateformat,$post[lastactivity]);
$post[lastactivetime]=vbdate($timeformat,$post[lastactivity]);

in postbit just add this where you want it to be displayed:
$post[lastactivedate] $post[lastactivetime]