Problem med switch

Kode 

<?php
class Quiz
{	
	//MAX NUMBERS OF QUESTIONS
	private $MaxQuestions;

	//CONTAIN QUESTIONS
	private $Questions;

	//QUESTION NUMBER (STARTS AT 1)
	private $QuestionNumber = 1;

	//CONTAIN ERRORS
	private $Error = 0;


	//CONSTRUCTOR
	public function __construct($MaxQuestions = 9)
	{
		$this->MaxQuestions = $MaxQuestions;

		if(!isset($_SESSION['Question']))
		{
			$_SESSION['Question'] = 1;
		}

	}


	public function CheckAnswer($Answer)
	{
		if($Answer == $this->Questions[$_SESSION['Question']]['Answer'])
                {
			return true;
		}else{
			return false;
		}

	}

	//SET QUESTION
	public function AddQuestion($Question, $Answer)
	{
		if($this->Error == 0)
                {
			//CHECK IF QUESTION IS A STRING
			if(is_string($Question))
                	{

				//CHECK MAXIMUM QUESTIONS
				if($this->MaxQuestions >= $this->QuestionNumber)
                		{

					//SET QUESTION
					$this->Questions[$this->QuestionNumber]['Question'] = $Question;

					//SET ANSWER
					$this->Questions[$this->QuestionNumber]['Answer'] = $Answer;

					$this->QuestionNumber++;

				}else{
					$this->Error(100);
				}
                	}else{
				$this->Error(101);
			}	
                }else{
			$this->Error(102);
		}

	}


	public function ShowForm($Question)
	{
		//SHOW IF THE ERROR IS NOT SET
		if($this->Error == 0 && count($this->Questions) != 0)
                {

			if(count($this->Questions) >= $_SESSION['Question'])
			{
				echo "<h1>".$Question." . ".$this->Questions[$Question]['Question']."</h1>\n";
				echo "<form action='' method='POST'>\n";
				
				echo "<input type='text' name='Answer' size='20'>\n";

				echo "<input type='submit' value='Accepter?' name='Button'/>\n";
				echo "</form>\n";

			}else{
				echo "<h1>No more questions..</h1>";
			}
		}else{
			$this->Error(103);
		}

	}


	public function Error($x)
	{
		$this->Error = 1;

		switch ($x) {
    		case 100:
       			$ErrorText = "There must be maximum ".$this->MaxQuestions." questions";
        		break;
    		case 101:
       			$ErrorText = "The answer was not allowed, or in the class array...";
        		break;
    		case 102:
       			$ErrorText = "The question must be of the type string...";
        		break;
    		case 103:
       			$ErrorText = "The form failed to be created...";
        		break;
    		default:
       			$ErrorText = "Error found";
		}

		echo "<div id='Error'>".$ErrorText."</div>";
	}

}
?>

Kode 

<?php
session_start();
include("quiz.class.php");

$Quiz = new Quiz();
$Quiz->AddQuestion("Spørgsmål1","1");
$Quiz->AddQuestion("Spørgsmål2","2");
$Quiz->AddQuestion("Spørgsmål3","3");
$Quiz->AddQuestion("Spørgsmål4","4");
$Quiz->AddQuestion("Spørgsmål5","5");
$Quiz->AddQuestion("Spørgsmål6","6");
$Quiz->AddQuestion("Spørgsmål7","7");
$Quiz->AddQuestion("Spørgsmål8","8");
$Quiz->AddQuestion("Spørgsmål9","9");


if(isset($_POST['Button']) && $Quiz->CheckAnswer($_POST['Answer']))
{
	$_SESSION['Question']++;
}else{
	echo "Wrong answer try again..";
}


$Quiz->ShowForm($_SESSION['Question']);
?>