title: Getting an error when calling createuser of Firebase
body: <p>I am getting this error</p>
  
  <p>Attempt to invoke virtual method 'void com.firebase.client.Firebase.createUser(java.lang.String, java.lang.String, com.firebase.client.Firebase$ValueResultHandler)' on a null object reference
              at com.test.test2.myfirebasetest.MainActivity.onClick(MainActivity.java:50)</p>
  
  <p>Can you please tell my what I am doing wrong?</p>
  
  <pre><code>public class MainActivity extends ActionBarActivity implements OnClickListener {
      TextView email, pass;
      Firebase myFirebaseRef;
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
          Firebase.setAndroidContext(this);
  
          Button register = (Button) findViewById(R.id.register);
          Button signin = (Button) findViewById(R.id.signin);
          pass = (TextView) findViewById(R.id.pass);
          email = (TextView) findViewById(R.id.email);
          register.setOnClickListener(this);
          signin.setOnClickListener(this);
          Firebase myFirebaseRef = new Firebase(**LINK**);
      }
  
      @Override
      public void onClick(View v) {
          switch (v.getId()) {
              case R.id.register:
                  myFirebaseRef.createUser(email.getText().toString(), pass.getText().toString(), new Firebase.ValueResultHandler&lt;Map&lt;String, Object&gt;&gt;() {
                      @Override
                      public void onSuccess(Map&lt;String, Object&gt; result) {
                          //do something
                      }
                      @Override
                      public void onError(FirebaseError firebaseError) {
                          // there was an error
                      }
                  });
                  break;
              case R.id.signin:
                  break;
          }
      }
  </code></pre>