In order to map financial objects to the Ledger, they must have an Account lookup field. This is because the Payee/Payor field on the Transaction object relies on the account field to populate in the Ledger. Some objects already have an Account lookup; however, the ones which do not can have a lookup added to them.
Adding Account Lookups to Financial Objects
Objects like Expense, Damage, Lien, and others will need Account lookups added to their Fields & Relationships section in Object Manager.
Access Object Manager by clicking the setup cog > Click Object Manager > Type the object which needs a lookup added in the Quick Find bar > Click [Object] > Click 'Fields & Relationships'
Click New > Select 'Lookup Relationship' > Click Next > Select 'Account' from the 'Related To' picklist > Click Next.
Allow the fields to auto populate > Click Next > Click Next > Click Next > Click Save > Click Cancel or exit the tab. The object will now have a lookup to Account and can be mapped properly.
