Document sequence type being prompted

Hello,

Document sequencing is enabled at the business unit level (General ledger definition).  Also the ledger groups in ledgers for a unit for this  business also have document type defined.

However, when a user attemps to validate a journal entry from a particular ledger group, there is message asking that user input the document type.

Why is this happening when the configuration appears to be all there?  Anywhere else I need to be looking?

Thank you.