How can I add an object to an array in Objective-C?

I am starting to program in Objective-C. I am using a book to learn the first basics. The given example is not working! I can not see the problem in my code.
It was not so hard to understand it, but it just won't work. But everything I found elsewhere, they added Objects like I did.
I don't know if the syntax changed? I am using the iOS 4.3 SDK and Xcode 3.2.6!?
This part fails:

[questions addObject: @”What is 7 + 7?”]; //FAILS
[answers addObject: @”14”];

The error message says:
/Applications/Quiz/Classes/QuizAppDelegate.m:32:0
Applications/Quiz/Classes/QuizAppDelegate.m:32: error: expected expression before '@' token

I would be really happy, if someone can help me! Thank you!

I attached the code as well!

Jules

Full code: .h:

#import <UIKit/UIKit.h>

@interface QuizAppDelegate : NSObject <UIApplicationDelegate> {

    int currentQuestionIndex;

    //The model objects
    NSMutableArray *questions;
    NSMutableArray *answers;

    //The view objects
    IBOutlet UILabel *questionField;
    IBOutlet UILabel *answerField;

    UIWindow *window;
}

@property (nonatomic, retain) IBOutlet UIWindow *window;

-(IBAction)showQuestion:(id)sender;
-(IBAction)showAnswer:(id)sender;

@end

Part code where it fails: .m:

#import "QuizAppDelegate.h"

@implementation QuizAppDelegate

@synthesize window;

-(id)init{

    // Call the init method implemented by the superclass 
    [super init];

    // Create two arrays and make the pointers point to them 
    questions = [[NSMutableArray alloc] init]; 
    answers = [[NSMutableArray alloc] init];

    // Add questions and answers to the arrays 
    [questions addObject: @”What is 7 + 7?”]; //FAILS
    [answers addObject: @”14”];

    [questions addObject: @”Was ist die Hauptstadt von Madagaskar?”]; //FAILS
    [answers addObject: @”Antananarivo”];

    [questions addObject: @”Was ergibt 5-2*2+6?”]; //FAILS
    [answers addObject: @”7”];

    // Return the address of the new object 
    return self;

}

-(IBAction)showQuestion:(id)sender{

//Step to the next question
currentQuestionIndex++;

//Am I past the last question?
if(currentQuestionIndex==[questions count]){

    //Go back to the first question
    currentQuestionIndex=0;
}

// Get the string at that index in the questions array 
NSString *question = [questions objectAtIndex:currentQuestionIndex];

//Log the string to the console
NSLog(@"displaying question:%@",question);

//Display the string in the question field
[questionField setText:question];

//Clear the answer field
[answerField setText:@"???"];
}

-(IBAction)showAnswer:(id)sender{

//What is the answer to the current question
NSString *answer=[answers objectAtIndex:currentQuestionIndex];

//Display it in the answer field
[answerField setText:answer];
}