Constructor

Can somebody tell me whats wrong with the following class?

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public class Account
 {
       private Key myKey;
       private String username;
       private String password;
       
       public Account(Chat serverRef, String user, String pass)
        {
           myKey = new Key(serverRef);
           username = user;
           password = pass;
        }
       
       public Account(Chat serverRef)
        {
              myKey = null;
              username = null;
              password = null;
        }
       
       public String getUsername()
        {
              return username;
        }
   
    public String getPassword()
     {
           return password;
     }
   
    public Key getKey()
     {
           return myKey;
     }
   
 
     
 }
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The problem is, I do smth like:

Account myAccount = new Account(aChatServerObject, myUsername, myPassword); // it is fine but not until I do:

Key temp = myAccount.getKey(); // then it returns java.lang.nullpointerException. Why is that??? I cant see whats wrong with that though~~~ Somebody?