MARKETPRESS, FRAMEMARKET, GRIDMARKET, WPML, shopping cart link direction

The cart is not working as it should and I'd be loosing 80% of willing buyers like this!

I am using the Marketpress-plugin, FrameMarket/Gridmarket-theme
I have setup WPML also.

Sofar I am using two languages: German and Dutch (no English sofar!)

problem description:

when a user has added products (please add one with variation)
to see the whole drama:

1. When you click on the "view Cart"(Mein Einkaufswagen=my string-translation to german of "show cart") on the Top-Left, the cart will appear.
Alright, sofar as it shows product & variation: product/variation
But, when you hover over the checkout(Zur Kasse) button on the right-bottom side of the sliding-cart, it still points at
with the result: Not Found...Sorry we could not find that page.

Guess that 80% would hook off here.

2. Only when I refresh the page (or click on "Mein Einkaufswagen" again), the correct link to respective languages cart
will appear, but also at the same time the variation has vanished & only "reappears" on respective "http://mydomain/store/order-status/" page or mail confirmation..

I musn't emphasise that this is crucial!