Invoice Number blank in Shipper screen

Hi All,

     In shipper screen we are giving our own distinct invoice numbers while 
creating the shipper rather than standart Solomon invoice numbers. we found 
that for the cancelled shippers the invoic enumber is becoming blank. 

    The situation is like, after you cancel & finish the shipper, process 
manager making the Invoice Number blank. Is this is correct? because we are 
facing problem in finding out the cancelled shippers searching by invoice 
numbers. 

      We are using - SL6.5, SP1.

Thanks