SELD during migo against STO

Hello Team,

In my scenario, material is mainatined as batch management. I have not mainatined SLED in batch master during the migo and there is no exist record for the batch master record for SLED. So during the migo , sled field gets empty in standard PO.

But if the same batch assigned during STO , then system will giving the error message " enter the SLED for the mentioned batch during migo against the delivery with refaerance to STO ( intercompany ).

Can u please tell me why system is asking for SELD during migo against STO .

Thanks