Lookups – One of the values you entered is required to be unique, but has already been used in another record in this lookup

Error Message

One of the values you entered is required to be unique, but has already been used in another record in this lookup.  Please enter a unique value, or press the delete button to remove the record.

Solution

Choose a new number.  The Lookup you are adding to already has the  Code in use.

Most Commonly Seen in Branch, Department or Pay code.