Hi Karthikeyan
try this and let me know if it worked, dubble click the global variable so you will see the global front panel, then put the mouse on top of the front panel relevent icon (what the global variable means on the front panel) and initialize it to the certain value you want everytime the VI starts running afresh, then wright click and go to "data operations" and in it to the option "make current value default" and chouse it!!!, after that save the global front panel and the program were the global variable is and that shoud to the job
good lock and tell me if it worked!!
SKI FARM