Cannot charge gift cards through Retail API

I've been struggling for quite some time with the gift cards through the Retail API.
I really hope someone can take a look at the situation below to see what I'm missing.
This is the situation;
1.
A new gift card is created through the API and linked to a customer ID.
This works fine, see print screen 1: request of the newly created CreditAccount via de API.
2.
Gift card is charged € 1 through the API with a completed Sale, following the tutorial.
See print screen 2: JSON of that call to Sale.json.
This Sale looks to be correct, see print screen 3.
Problems :
- No trail of this gift card can be found in LightSpeed (print screen 4).
- The balance of this gift card stays at "0".
Thank you.