Hi Suma,
To know the error of your DTP, there is an option in the EXTRAS or SYSTEM wherein you can read something like "GENERATE" (if I'm not mistaken,3rd option from the top) then you must check all boxes (I think there are a total of 4 boxes)..Sorry could not tell you the exact option since I'm at home,I will check it tomorrow..
After checking all the boxes, reload your DTP to get again the error and you will have a MAGNIFIER beside the error message then you will see the exact error message..
Regards,
Loed