E1 Multiple Shipment Number in one Sales Order

Hi,

I am facing subjected issue while entering the sales order in below scenario -

Item Number        : A, B, C & D

Ship To & Sold To : Are Different Address Numbers

Route Code          : Same

Shipment Date      : Same as Order Date

When i enter the sales order for above 4 item number with same Order/ Shipment date, the shipment number gets populated in Order detail line against all the 4 lines. But the shipment number populated against 2nd line (Item Number "B") always be different than rest of the 3 lines ( same shipment Number appears against rest 3 lines i.e. against item A,C,D).

Even if verified the shipment Date, Routing Restriction (NO Restriction applied).