Seemingly you have selected only one “half” - when you try to Post, Navision doesn’t warn you that other “half” must be selected, too. Instead, looks like posting is in progress, but it ends up with message you quoted.
I set in the Applie to ID, the Applying Entry and i also filled the information regarding the Balance accounts. Still not enough? In the NAV 838X_NA40_ENUS_FSI_FI training material there is nothing mentioned about this problem.
You can apply, for example, Invoice to Payment (or CreditMemo, in short Db to Cr or vice versa) - these are 2 “halves”
Another possibility - if an Invoice is selected as Applying entry, and you set F9-Applies to ID to another Invoice, not Payment (or CreditMemo), the same happens.
How are you assigning the “Applie- to ID” - by manually entering (using F2) it does not update all the requied fields. You you using Application → Set Applies-to ID (F9)?
First, select one of Lines as Applying Entry (shortcut = Shift-F9) - it’s data then appear in “header” part of Form, and is removed from “list” part.
Then, for one or more lines the only field to fill is Applies-to ID (shortcut = F9, toggles the mark) - so you mark which line(s) will be applied against the one selected in first step.
Ok, but in the list part I only see unpaid invoices. There is no payment in the list. So with this window I can reconcile the partner balance? From this window I cannot make payments for a certain invoice?
No. This form lists all posted transactions with Vendor - Invoices, Payments, CNs - and is used for apllication ONLY - it is even named Apply Entries… You can not add new transactions here - be it Invoice or Payment.