Group-prices isn't getting added to the cart

Question

I have some products, where there are some normal prices, but when logged in as a customer (in a specific group) the prices changes. These price-changes works fine on the product-view, but when adding a product to the cart, the price is the same as the "logged-out"-price.

Why isn't the group-price getting added to the cart?

Thanks in advance

Answer 1

I figured out why. It had something to do with the function "Automatic Group Change Based on VAT ID". So when I disable this, it works perfectly!