How did you get to this payment entry screen? Did you click on the New Payment button while viewing a purchase invoice? Or did you create it from scratch?
Please post a screen shot of the Edit screen for the purchase invoice you are paying.
Also post a screen shot of the Edit screen for Faktur Penjualan #333.
The trouble seems to be a translation error. Your payment form clearly matches the supplier, invoice number, and payable amount of purchase invoice (faktur pembelian) #333. But the invoice selection field is labeled as a sales invoice (faktur penjualan).
Switch your language preference to English temporarily. See if the problem goes away, with the payment form showing sales invoice #333. If so, I will put this into the bugs category as a translation error.