Link between Payment Terms and Posting Key

Hello,

I wanted to know if there is a link between Posting Key and Payment terms.

The problem is when i'm posting Bills of Exchange payment (F-36), in the second line item, i put the following data:

- Posting Key : 16 (Payment difference)

- Account: Customer Account

I click enter, and i don't have the payment terms field fulfilled per default (the payment term is defined in the customer master record)

But with the posting key 14 it works correctly.

In advance, Thank you all

Tarek