"And, yes I tried to use DS51. With debugger everthing seems OK."

DO you mean it "works" OK in a simulator?

When stuff works in a simulator, but not in the real target, this usually indicates either
1. There's a fault in your hardware, or
2. You have misunderstood the hardware, and what you think looks "right" in the simulator will not actually work (correctly) with the real hardware.

Dan has already given an example of 2; how have you verified that your hardware is all OK to eliminate 1?