Able to post transactions with BSV that's not included in the ledger

In AP Subledger - I have a US Ledger transactions that have entries for the BSV that's under CAN Ledger, still the system  create the accounting without any error.  I was expected to get the following error -

'Either update the balancing segment value assignments for the ledger US Ledger or update the balancing segment values used on the subledger journal entry.'

Why it's error out ? Why did the system let the transaction post with LE that belongs to another ledger ?