My client has EDI setup for POs for a vendor. Whenever they create a PO for a specific material with Ordering UoM as 'CAR' (carton), output is going into errors and no Idoc was generated. The error message refers to 'ME764' - "Not possible to determine ISO code for unit of measure CAR in item 00090". But, ISO code was perfectly defined for the UoM CAR (I checked in CUNI). When debugged, I found that the UoM CAR has an internal format as 'KAR' and SAP standard function module 'UNIT_OF_MEASURE_SAP_TO_ISO' is looking for ISO code of 'KAR' and throwing this error message for 'CAR'. Have you guys ever faced similar problem and any solution for this behaviour? We use SAP ECC 6.