Add to cart button in free products


I’m using Cs-Cart 1.3.5 Sp1 and I sell downloadable products. Sorry for my English, I don’t speak it fluently.

I have some free products in the shop that can be downloaded directly in the page and the user does not have to add them to the cart, but I have a problem because the Button “Add to cart” appears even when I specify in the options that when price is zero the user can not add the product to the cart…

I’m using the basic skin and This was not the case in Cs-Cart 1.3.4 because the button didn’t appear when price was zero (I was using then another skin).

I’d like to make disappear the “Add to cart” button because it’s a bit annoying, the user press the button in the free products and becomes disoriented because the message of “cart empty”, and by the way it alters the statistics of people that push the “Add to cart” because he likes a paid product.

Some insight to fix this?

Thank you very much.