Bug with combinations? Size and color selector

[paraglidingstore]

Hi...
A strange situation in presta 1.2, or a BUG?… I have products with different colors, different sizes and different prices, with prices depending only of the color.. When I introduce the one color selector (in the combinations), the prices change normally in frontend, but if I introduce one size selector, the price doesn’t change anymore…even if I try to make all possible combinations between color, size and price.
Please, check both situations in my site here, and look at the price: http://www.paraglidingstore.net/product.php?id_product=11 <- here price is ok
but here-> http://www.paraglidingstore.net/product.php?id_product=10 price doesn´t change anymore, and it tells that product is not available… it seems that presta it is not able to do the correct relation between the color and size, with price, or may be in consequence of the quantities or the procedure to bild the combination is wrong. Any idea of what can be? Probably something wrong with my procedures. Any help would be welcome and very apreciated.

Thanks in advanced for any help
Cordially
Henrique