Android Toast Message is not showing

Try:

Toast.makeText(getBaseContext(), "Reason can not be blank", Toast.LENGTH_SHORT).show();

It's the .show() that you've omitted everywhere that causes all your toasts to instatiate, but never execute.

I think you are missing .show(); It should be...

Toast.makeText(getBaseContext(), "Amount can not be grater than invoice",
                                                     Toast.LENGTH_SHORT).show();

Please excuse me if this isn't the solution to your problem, but I accidentally unchecked the 'Show notification' setting of the application once. It may be an idea go into your device settings/application/manager and check this setting.