Adding field attributes to product does not display in product display node
I did follow the steps written in http://www.drupalcommerce.org/faq/product-attributes
I have two fields - field_size and field_color. Although I create a product that has sizes and colors to it for attribute selection, it still doesn't display in the product display node although I've "Enable this field to function as an attribute field on Add to Cart forms.". As for product display node display settings, I've tried tick and untick "Show attribute widgets even if the Add to Cart form only represents one product." which doesn't work as well. It only shows the select box to select different products referenced to it rather than attributes.
Am I missing something here?