ITEM_CATEG is not provided for this Item bapi_salesorder_createfromdat2

Hello Experts,

i am calling the fuba bapi_salesorder_createfromdat2.

Everything works fine, untill i add any ITEM_CATEG.

After calling the fuba, i get a return mssg: "Item category XXX is not defined for this item."

When i leave it empty.

The Order gets created with the item_categ ZATN.

When i try it again, by filling the item_categ with ZATN, i get the same error.

Thanks for any Help!!!

Luis