Dear Krishna.
You created new flow type - additional configuration is needed:
IMG -> SAP Customizing Implementation Guide -> Financial Supply Chain Management -> Treasury and Risk Management -> Transaction Manager -> General Settings -> Accounting -> Link to Other Accounting Components -> Indicate Update Types as Relevant to Posting
Mark update type for flow type as relevant to posting.
IMG -> Financial Supply Chain Management -> Treasury and Risk Management -> Transaction Manager -> General Settings -> Accounting -> Link to Other Accounting Components -> Define Account Determination ->
Don't forget to assign posting spec and accounts to update type of flow type.