Current Scheduled Receipts in Horizontal Plan

Hi Friends.

Firm Purchase Orders (ie Firmed in Purchasing module and collected via data collections) for an item and when reviewing the horizontal plan the firm PO's show up in Current Scheduled Receipts and their quantity is taken into account for Projected On Hand. when double on Purchase order field and Current Scheduled Receipts and show up same purchase orders some time but some POs are not showing in current Scheduled Receipts.

If we refer date on 18-Nov-2015. There are 10 POs in Purchase order field but same orders are not available in Current Scheduled Receipts.

How Current scheduled receipts calculated and showing the fields? what is the calculation of Projected On hand