There is nothing wrong with the code loading,
>>i can only setpup prices to variations. and in the frontend i see every time the lowest price for all variations!
this says to me that your variations are setup incorrectly, it sounds like you have added an extra variation without selecting what attribute it is assigned too.
if you can post a screenshot of the item with all the variations expanded so i can see them, ill be able to tell you which one is wrong.