is_int problem ?

[eluser]Spleshmen[/eluser]
my third uri segment is a number and before i use it i need to check so i am using is_int but its not working ,any chance some one can help me fix this?thanks

Code:

$id = $this->uri->segment(3);
echo $id; //it displays the number from my url
if (is_int($id)==TRUE)
echo 'working';
else
echo 'not working';