Bin location default Bin on OITW

Hi Expert

i've to update the default bin for all item in OITW, but if i try to update the system give this error messagge:

the item already exist. i try to find  the correct linenum for item already insert in database, but  the errore messagge it's the sap

i've sap 9.0 pl08 and in dtw's template i find the field

can anyone help me?

i upload the file.