Trigger på submit problem

Halløjsa derude.

jeg har lavet mig en opret form på mit site, og selv koden efter er der ingen problemer med, den smider brugerens info ind i min database.

Men jeg kunne godt tænke mig at det hele kørte på min index.php , har prøvet if($_POST('formnavn') {} men den er ligeglad.

i kan lige få min kode, paster bare formen + validering koden, som ikke virker.

<form method="post" name="register">
<table width="160px" border="0">
<tr>
<td style=" text-align:center;">
	<p><b> Username </b></p>
</td>
</tr>

<tr>
<td>
    <input type="text" name="username" class="form" />
</td>
</tr>

<tr>
<td style=" text-align:center;">
    <p><b> Password </b></p>
</td>
</tr>

<tr>
<td>
    <input type="password" name="password" class="form" />
</td>
</tr>

<tr>
<td style=" text-align:center;">
    <p><b> Re-enter  Password </b></p>
</td>
</tr>

<tr>
<td>
    <input type="password" name="re-password" class="form" />
</td>
</tr>

<tr>
<td style=" text-align:center;">
    <p><b> Email Address </b></p>
</td>
</tr>

<tr>
<td>
    <input type="text" name="email" class="form" />
</td>
</tr>

<tr>
<td  style=" text-align:center;">
    <p><b> Age </b></p>
</td>
</tr>

<tr>
<td>
    <input type="text" name="age" class="form" />
</td>
</tr>

<tr>
<td style="text-align:center">
    <input  type="submit" value="" class="submitbut" />
</td>
</tr>

</table>
</form>
    


<?php }	

	if($_POST['register']) {
	
		$username = $_POST['username'];
		$password = $_POST['password'];
		$repassword = $_POST['re-password'];
		$email = $_POST['email'];
		$age = $_POST['age'];
		
			
		if($password != $repassword) {
			echo "Entered passwords is not identical";
			header("location: index.php?ps=register");
			exit();
		}
			
		$valUsername = mysql_num_rows(mysql_query("SELECT * FROM users WHERE username = '$username'"));
		if($valUsername == 1) {
			echo "Entered username is already taken";
			header("location: index.php?ps=register");
			exit();
		}
		
		$valEmail = mysql_num_rows(mysql_query("SELECT * FROM users WHERE email = '$email'"));
		if($valEmail == 1) {
			echo "Entered email is already in use";
			header("location: index.php?ps=register");
			exit();
		}
			
		if($age < 16 ) {
			echo "Users of Paradise Undone, have to be aleast 16";
			header("location: index.php?ps=register");
			exit();
		}	
		
		
		// Hvis der ikke er nogen problemer, smider vi brugeren i systemet.
		
		mysql_query("INSERT INTO users (username, password, email, age) VALUES ( '$username', SHA1('$password'), '$email', '$age')") or die(mysql_error());
		echo "Your user have been created, and ready for login entry";
		$oprettet = true;
}

Jeg ved ikke om det er mig der er uvidenede mener bare det er sådan man får den til at trigger, håber i kan hjælpe mig.