J1IA101 invoice items not appearing

Hi Experts

I am an abap person with limited functional knowledge . An invoice was created and we ve tried to post it in J1IA101 to create ARE . The invoice has 3 line items whereas only 2 have been displayed when we give the refernce number for the invoice and display it .The 3 line items have different delivery numbers . CAn somebody brief the process from invoice creation to creating ARE.Thanks in advance .