benchmark classes not working :(

[eluser]natefons[/eluser]
it sed to work before, but, i had this code:
$data['time'] = $this->benchmark->elapsed_time();
$data['mem']= $this->benchmark->memory_usage();

that would display time and memory data...but now all of a sudden it doesnt seem to want to do that, instead is displaying its sudo code:
{elapsed_time}
{memory_usage}