I see several problems.
- You initialize the received message variable to 'O', so your app is going to buzz immediately. Better to initialize it to blank.
- Read the tool tip for Clock1.TimerInterval. It is in milliseconds, not seconds, so you are setting the clock to run 1000 times too fast. Just use 250.
- You don't need to reset the Interval every time it fires. You can do it once in Screen1.Initialize or the Designer's Clock1 Attributes.
- You have to wrap that ReceiveText sequence with a test if BytesAvailable > 0. Don't attempt a ReceiveText unless you are sure there is text waiting in the BlueTooth buffer.
- That vibrate for a full second might be trouble. Test and let us know how that worked out for you.