php index file blank when using functions

Question

I have finished my site and uploaded it on a free webhosting this is what it shows http://baseet.info/caht/ blank page although I have this code in it :

<?php
  function classLoader($class_name){
  }

  $get_var = array_keys($_GET);
  $init_class = (!empty($get_var[0])) ? $get_var[0] : "Index";
  echo"asd";

  if (preg_match('/^[A-Za-z0-9_\-]+$/i',$init_class)){
     echo "Asd";
  }
  else{
    echo "Not allowed sign in the class name!";
  }
?>

i tried to remove the function and it worked? Why is it happening?