matching error in manual supplier invoice

Hi, 

Could you check whether you followed below steps. 

1. Copy the PO number and search that in ‘receipt’ window to make sure you only have that receipt of 15 items. 
2. Go to manual supplier invoice window and add new. 
3. Past the PO number in ‘PO’ ref field. 
4. Add the invoice number
5. go to the line information section and RMB and select ‘copy unmatched PO receipts’ option. Ideally if you have received only 15 items, you should only be getting the records correspond to 15 items.
6. Match the PO receipts and Post the invoice. 

Thanks,

Thushan Wijayawickrama