Hi Rushikesh,
Check whether you have maintained the table V_T7INAPRR_LVL , V_T7INAPRLVL_GRN and then you need to implement the BADI - HRPBSINGET_APPROVER.
Actually after the submission of request in ESS the system calls this BADI to determine the approver level. Implement the BADi your issue will be resolved.
Regards,
Mithun K