this is in a file called functions, right now it is the only thing in there besides my mysql connection.

function protect($string){
	$string = trim(strip_tags(addslashes($string)));
	return $string;
}

i include it here on my other page.

<?
session_start();

if(($_POST['check']) == $_SESSION['check']) {
	echo $_SESSION['check'];
				}else{
					echo 'Your CAPTCHA numbers are incorrect.';
					}
include('functions.php');
?>

and this is where im using it on the same page.

		if(isset($_POST['submit'])){

			//protect and then add the posted data to variables
			$username = protect($_POST['username']);
			$password = protect($_POST['password']);
			$password2 = protect($_POST['password2']);
			$email = protect($_POST['email']);
			$permisson = protect ($_POST['permission']);
			$agree = protect ($_POST['agree']);

im getting this error:
Fatal error: Call to undefined function protect() in C:\inetpub\wwwroot\register.php on line 69

which is this line:
$username = protect($_POST['username']);