updating or changing the outbound delivery

Hi

we have created a outbound delivery in the system, I want to update some of the detials like route, no of packages using a program. is there any FM or BAPI for that. I have tried using the BAPI_OUTB_DELIVERY_CHANGE to update the route in the delivery. But somehow it is not updating and the BAPI does not give any error message also.

thanks

sankar