Message type: E = Error
Message class:  FKKBIX2 - Billing in Contract Accounts Receivable and Payable 
Message number: 127
Message text: Search help for source transactions of type '&1' is not supported
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The SAP error message FKKBIX2127 indicates that the system is unable to provide a search help for source transactions of a specific type (denoted by '&1'). This typically occurs in the context of financial transactions, particularly when dealing with document processing in SAP.
Cause: Unsupported Transaction Type: The error usually arises when the transaction type you are trying to search for does not have a defined search help in the system. This can happen if the transaction type is custom or not commonly used.
Configuration Issues: There may be configuration settings in the SAP system that do not support the search help for the specified transaction type. Missing Authorizations: Sometimes, the user may not have the necessary authorizations to access the search help for certain transaction types.
Solution: Check Transaction Type: Verify that the transaction type you are trying to use is valid and supported. If it is a custom transaction type, you may need to
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