[SOLVED] BC - Charge Item from Purchase Document to Sales Document

Scenario:

I have a sales order with one line
Quantity 1
Price 1000 €

The sales order is delivered and invoiced.

Now I create a purchase invoice with a charge line of €100 and charge this to the sales shipment.

When I post the purchase invoice, I receive a g/l entry of €50. But the corresponding value item is negative.

According to this logic, the purchase price has not increased but decreased when the sales item is considered.

If you create the same case with a purchase credit memo, it behaves exactly the other way round, so that the credit memo is shown as an expense in sales (purchase price positive) instead of as revenue.

If the charge is divided equally between a purchase and a sales, the sum of the value entry is 0.

Can someone explain to me why the BC Standard does it this way?