To make Payment OR Pre payment of SO follow the steps below:
1- First, create Sales Order
2- Go to Payment journals (Accounts receivable/Common/Payments/Payment journals)
3- Select Button Payment journal then click New Button for create new payment.
4-Select new payment and click Enter Customer Payments Button.
5-Fill Enter Customer Payments form and click Button Save in journal.
-Payment reference: it is Sales Order number.
6-When you select the customer , system show all of open orders.you can select to pay.
7-Finally, post it.
8-For see and check amount of Prepayment,go to All Sales Order and select SO then select Action oane sell and click Prepayment Button.
Regards
Hossein Karimi