Message type: E = Error
Message class:  FKKBIX - Conv.Inv.: Billing (Invoice Preprocessing) 
Message number: 513
Message text: Consumption item class &1 not usable productively
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The SAP error message FKKBIX513 indicates that a consumption item class (specified as &1 in the message) is not usable for productive purposes. This error typically arises in the context of SAP's Financial Accounting (FI) and Controlling (CO) modules, particularly when dealing with consumption items in the context of internal orders, cost centers, or other financial transactions.
Cause:
Configuration Issues: The item class may not be properly configured in the system. This could be due to missing settings or incorrect parameters in the configuration of the item class. Status of the Item Class: The item class may be set to a status that does not allow it to be used in productive transactions. For example, it might be marked as "test" or "inactive." Authorization Issues: The user may not have the necessary authorizations to use the specified item class in productive transactions. Master Data Issues: The master data associated with the item class may not
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