Cart letting them check out without seleting attribute

I am wonder if/how I can make it so they can not add a probuct to cart without selecting the attribute given. I have the items in the cataloge markes as "priced by attribute" The attributes I created trying both radio buttions and check boxs but still you can add product to cart with selcting any attribute. Then is shows up as costing 0.00 and it will let you checkout.

The site i am using this on is https://www.petnaturalsdirect.com

This is a link to the only product i have add so far as I did not want to go futher untill I make sure this is right
http://petnaturalsdirect.com/index.php?main_page=product_info&cPath=1_3&products_id=4

THanks

Matthew

Did you get this worked out?

create another value for the list called "Weight of Dog" or what ever works for you add it as an attribute to the list sorting it to the top of the list. Make this new attribute the default and for display purposes only. That way if they try to add to cart without picking an attribute that can be purchased the page will display an error letting them know that they have to pick an attribute. Make any sense.......

Yes that does make since I will try that and see what happens.

Thanks

Matthew

Thanks that works great. I knew there has to be a trick to make it work.

Thanks!