Product variation on apparel product created from image content type doesn't work.

Steps to recreate problem:

• create content > image
• type image title
• browse for image
• select category (if present)
• click submit
• click "edit" tab
• click "product" link
• click "apparel" product radio button
• click "Add to store"
• enter price
• click submit

Despite the fact that it's an apparel content type, there's no "subproduct" tab on the newly created product. Am I doing something wrong?