Serial number profile assignment in delivery

Dear Friends,

We have a delivery created and when we try to assign the serial number, the system throw an error stating that "serial number profile missing for the material in the plant". So we assigned the serial number profile in material master and tried to give the serial number in the existing delivery to which the system is giving the same above error! After debugging we could find that serial number profile is still missing in that delivery even after assigning the profile in the material master!! Please let me know is this a standard behaviour and how do we proceed with assigning the serial number in the existing delivery? Or is there anyway to assign the serial number profile in the existing delivery?

If we create another delivery for this same material serial number can be assigned but not with the all the existing deliveries created when there was no serial number profile assigned in the material master!!

Regards

AW