Android and Paypal API integration

I'm trying to integrate the Paypal API to make my app donation based. I have two questions:

1. I can see the button, I click it but it doesn't do anything! (the activity for checkoutIntent doesn't fire?)

2. What are your experiences with donation based android apps? I want to make about $250 a month of this thing, is that even possible?

public class Donate extends Activity implements OnClickListener {     PayPal ppObj = PayPal.initWithAppID(this.getBaseContext(), "APP-80W284485P519543T", PayPal.ENV_SANDBOX);     @Override     public void onCreate(Bundle savedInstanceState) {      super.onCreate(savedInstanceState);      setContentView(R.layout.donate);      LinearLayout mainLayout = (LinearLayout)findViewById(R.id.LinearLayout01);      if (ppObj == null) ppObj = PayPal.initWithAppID(this.getBaseContext(), "APP-80W284485P519543T", PayPal.ENV_SANDBOX);      CheckoutButton payPalButton = (CheckoutButton) ppObj.getPaymentButton(PayPal.BUTTON_294x45, this, PayPal.PAYMENT_TYPE_HARD_GOODS);      payPalButton.setOnClickListener(this);      mainLayout.addView(payPalButton);     }     public void onClick(View arg0) {      PayPalPayment newPayment = new PayPalPayment();      newPayment.setAmount((float) 1.00);      newPayment.setCurrency("USD");      newPayment.setRecipient("example@example.com");      Intent checkoutIntent = new Intent(this, PayPalActivity.class);      checkoutIntent.putExtra(PayPalActivity.EXTRA_PAYMENT_INFO, newPayment);      this.startActivityForResult(checkoutIntent, 1);     }     @Override        public void onBackPressed() {      Intent menuIntent = new Intent(Donate.this, MTGTools.class);         this.startActivity(menuIntent);        }    }