EKET table question

EKET table is for "Scheduling Agreement Schedule Lines"

in field EBELN in EKET table if I give purchase order details, it gives me output

but if I go to t-code ME39 (Scheduling agreement) and give the same PO number it gives "Not possible to process a purchase order using this function"

If I cannot process a purchase order document from ME39 t-code which is to display scheduling agreement, why does EKET table which is meant for scheduling agreement scheduling lines giving me an output for the purchase order?