Installed Base WIP Assembly Return

Hello,

 

I wanted to understand what exactly the WIP Assembly Return transaction means. For an item in Installed base transaction history shows the transaction type as - WIP Assembly Return by which user is not able to create a service request for that item and serial number combination.

Initially the item is WIP completed and a sales order is created to ship the item for a customer and for that item next transaction says WIP Assembly Return and causing an issue where user can't create an service request for it.

Any help to fix this issue is appreciated!!!

Thanks for your help in Advance.