Item Instance Serial Number cannot be updated to a Null Value

Hi,

For a sales Order, one of the line is struck at Interfaced to Receivables. The item is serialized at Receipt. When I query the item in

Install Base Administrator responsibilioty --> Transaction Error Processing Form --> Queried the item

The serial number is reflecting in corresponding Install Base tables,

csi_item_instances 

csi_t_txn_line_details

I found the error message as "Item Instance Serial Number cannot be updated to a Null Value".

Can you please suggest what could be the possible  root cause for this issue ?

Regards,

Jagadeesh Tata