I am using a blueTooth module and HDT11 for a home automation project.
The HDT test program stop working when the TX and Rx pins connected to the bluetooth module.
But worked fine when only connected with HDT11.
Why would the program stop working? and what should I do to make the bluetooth work?
Well, most likely your bluetooth module is faulty.
I guess in all fairness there is a smaaaaaall chance that your program is at fault too.
Maybe before you send the bluetooth unit back for repair, you could post your code here so we can all have a look at it for you. That way you'll be sure you're not wasting your time.
Hi,
Can you test the bluetooth with a simple program on its own?
The problem could be a clash of libraries, they may be trying to use the resources such as timers.
Can you please post a copy of your sketch, using code tags?
They are made with the </> icon in the reply Menu.
See section 7 http://forum.arduino.cc/index.php/topic,148850.0.html
Tom.... 
PS
Please go and edit the subject to this thread to, "Bluetooth and HDT11 not working together."
Because you started the thread you can go and edit it.
The subject you have tells anybody looking at the list of subjects nothing about your problem.
If you edit your subject to what I have suggested, you may get someone who has used these two items before.
The forum members do not open and read every thread.