Ahh, I see your issue. What you need to do is edit your product. Check all of the product tabs and make sure that everything is set up properly. A common mistake is to change the type of product when it should not be changes. It looks like in your case that for a tshirt, you want a VARIABLE PRODUCTS.
I am using a StudioPress theme.
I have set up a Product with two variations.
When I go to the live page, and select one of the variations, the ‘Add to Cart’ button (+ # of items, etc.) doesn’t show up.
My add to cart button won’t show via mobile devices. I had to install WordPress Mobile Pack because my website wouldn’t show via mobile devices without it. I tweaked the CSS and got everything looking decent only to have someone tell me they couldn’t check out because the add to cart button won’t show. Any ideas as to what I should do?