wats wrong here...

Code:
<?php

require ('header.php');

echo '<div class="register">';

if (isset ($_POST['submit']))
{
	$problem = FALSE;
	if (empty ($_POST['first_name']))
	{
		$problem = TRUE;
		echo '<p>Please enter your first name.</p>';
	}
	if (empty ($_POST['last_name']))
	{
		$problem = TRUE;
		echo '<p>Please enter your last name.</p>';
	}
	if (empty ($_POST['email']))
	{
		$problem = TRUE;
		echo '<p>Please enter a valid email address.</p>';
	}
	if (empty ($_POST['username']))
	{
		$problem = TRUE;
		echo '<p>Please enter a username.</p>';
	}
	if (empty ($_POST['password']))
	{
		$problem = TRUE;
		echo '<p>Please enter a password.</p>';
	}
	if ($_POST['password'] != $_POST['confirm'])
	{
		$problem = TRUE;
		echo '<p>Your password did not match your confirmed password.</p>';
	}
		if (!problem)
		{
			if ($fp = fopen ('../users/users.txt', 'ab'))
			{
				$dir = time() . rand (0, 4596);
				$data = $_POST['first_name'] . "\t" . $_POST['last_name'] . "\t" . $_POST['email'] . "\t" . $_POST['username'] . "\t" . crypt($_POST['password']) . "\t" . $dir . "\r\n";
				fwrite ($fp, $data);
				fclose ($fp);
				mkdir ("../users/$dir");
				echo '<p>You are now registered and can take advantage of all the features on our site!</p>';
		} else {
		echo '<p>You could not be registered due to a system error. Please try again later.</p>';
		}
	} else {
	echo '<p>Please try again!</p>';
	}
} else {

?>
	
<form action="register.php" method="post">
      <fieldset>
      <legend>
    	Register with us:
      </legend>
<p>First name:
		<input type="text" name="first_name" value="<?php if (isset($_POST['first_name'])) echo $_POST['first_name']; ?>" /><br />
Last name:
		<input type="text" name="last_name" value="<?php if(isset($_POST['last_name'])) echo $_POST['last_name']; ?>" /><br />
Email:
		<input type="text" name="email" value="<?php if(isset($_POST['email'])) echo $_POST['email']; ?>" /><br />
Username:
		<input type="text" name="username" value="<?php if(isset($_POST['username'])) echo $_POST['username']; ?>" /><br />
Password:
		<input type="password" name="password" /><br />
Confirm password:
		<input type="password" name="confirm" /><br />
	

	<input type="submit" name="submit" value="Register" /></p>

</fieldset>
</form>
</div>';

<?php

}

require ('footer.php');

?>
its probably the stupidest thing im overlooking but yea i cant find it
everytime i fill it out correctly it displays please try again instead of the u are now registered part