Hi Ravi
Hardcoded/Session/External breakpoints will not work, when the program is executed in the background. The system just skips them. The DTP processes the transformation in background by default. Try to run the DTP in simulation mode, so the transformation program is started in dialog.
In case you need to stop at a specific routine, put there an infinite loop (DO..ENDDO) and then you can jump into the debugger from SM50/SM66.
br
Roland