Using more than 1 programs.

I have assigned some chopped samples to my program(program 1).I record a 4-bar loop,and then I want to add some drums.I make a new program(program 2) and assign my drum sounds to it.My problem is that after changing to program 2,so I can add the beat I can't hear what I have recorded from my program 1.That means that I can only listen to 1 program at the same time.I searched my manual but I didn't find any results.Can you please tell me how can I have more that 1 programs playing at the same time?

Track 1: Program(Samples)
Track 2: Program(Drums)
Just go to your new track and next to that you can choose a new PRGM.

Thanks alot,you are a life saver shrednar.