Hello Siva,
you have to loop the material and pass it one by one and collect the details in another internal table for further processing, you can't give mass input to that in a single time. Because I've used this FM. it behaves always in such way. So use FM inside the loop and collect it an internal table whatever details required.
Answer to question:
You can't give more than one material no even in debug mode, you have to write a program to achieve this.
Hope this will be helpful for you.
Regards,
Balanand S