Finally I solved this problem by my self and the problem is that the header byte which I am sending to the printer is the real culprit. Actually I am sending 170,1 (where 170 is the first byte that the printer must receive and the second byte is the printer id I mean some com port which these two values are given by Printer control card designer). Actual I have to send 170,2 where 2 is the Printer Id so that it gives the correct print and for every printer it is common of sending the data based on their control card's.
Thanks a lot friends and here is my code that u can use these code for all types of printers(for POS-Thermal Printers)