I got the answer from SAP,
"If my understanding is correct, you are trying to post idoc's via WPUUMS for non valuated articles such as bottles/coupons? If no sales price exist for the coupon / bottle, no goods movements can be posted for an article subject to value-based inventory management. A sales price must exist for the coupon/bottle in order to process the idoc."
Thanks,
Suraj Pabbathi