Cause :
System shows the error ‘VTUNIT2’, ‘ Invalid unit’, ‘Unit of measure not defined, rate unit and standard unit are different’. When the item selected and unit and rate is blank or is not populated after the item is selected.
Remedies:
Users should check the units and rate for the line items added. Units and its rate should get populated once the item is added and quantity is entered.Need to ensure it’s not blank. If a particular item shows an invalid unit then users should delete the line item and add again. After this the user should do the split and finish the transaction.
Read more further about what are the details visible in split window Sales return form?