why you are leaving previous company?

Normally all are leaving for salary hike.  but you should 
not tell this reason.  you can tell the advantages of the 
new job with Ur current job. 
simply say i am looking for a betterment in my career and 
also i have some goal ( according to Ur job u can tell that 
u have one goal ...) to reach my goal i am expecting this 
new job ( tell some good points regarding new job)...