I need to import general journal lines for customer with combination of financial dimensions ,I am unable to get the ledger dimension recid for the combination of custAccount and financial dimensions.
so could you please let me know if there is any possibility for it.
If you are using account type as customer then your ledgerDimension will only have the customer account. You need to fill the financial dimension in DefaultDimensoin field.
Try creating a journal line manually and check.
BTW, please always tag your AX version.