First, I manualy created two products with variations. Then I export it and when making new products in .csv I just copy variations (under wpsc-variation) to new products.
But inserted products don't have variations.
In UTF-8 value of column wpsc-variation is "velkost:Velkost,velkost~10x13:10x13,velkost~15x19:15x19"
When I export all products, including the new products with variations in imported csv, in exported csv THEY HAVE VARIATIONS.
More interesting is, when I go to web and I open this product - there ARE variations to select, but when I select one I will get "Combination of product variants is not available".
Thanks for help.