To debug a smartform in quality or testing system, go to tcode SMARTFORMS. Enter the name of the smartform if you know or find the name of the smartform name from NACE and display the smartform.
Find the statement in the smartform where you want to place the break-point.
Go to menu Environment –> Function Module Name to get the name of the function module for the Smartform.
Copy the function module name in the popup. 
Go to tcode SE37 (Function Builder).
Enter the name of the function module and go to Menu Goto –> Main Program.
In the Main Program click on FIND to search the statement where you want to place the break-point.
Enter the text of the line where you want to place the break-point in the FIND popup.
Place the break-point on the desired line.
Now run the driver program, the control stops at the break-point and you can analyze the smartform.
is there is any another way to debugg the smartforms?