ONCE TRY BELOW
For TS21500003
APPLICATION hress_a_ptarq_leavreq_appl
DYNPARAM WI_ID=${item.externalId}
NAMESPACE: sap
SYSTEM_ALIAS: SAP_ERP_HumanResources
For TS21500004
APPLICATION hress_a_ptarq_leavreq_appl
DYNPARAM LRF_REQUEST_ID=${item.REQUESTID}
NAMESPACE: sap
SYSTEM_ALIAS: SAP_ERP_HumanResources
check above in once SWFVISU FOR THE ABOVE PARAMETERS
As per the standard add-on provided by SAP, the System Alias for Leave request isSAP_ECC_HumanResources.
Hence check the alias for Leave request at the Tx: LPD_CUST and maintain the same.
So make sure that both Application alias & Portal/System alias) to be same.