Issue with POR_CUSTOM_PKG hook

I am trying to capture whether Req is internal or purchase and then populating some default value on the lines. I am using POR_CUSTOM_PKG.CUSTOM_DEFAULT_REQ_LINE procedure and taking the req_header_id and finding from po_requisition_headers_all whether it is internal or purchase req. Issue here is when ever I add 1st line I am not finding any record in headers table for that req_header_id to to find whether req is Internal or purchase but when i add second line then I am seeing the data in the po_requisition_headers_all table.