1- Is your customization page defined as homepage?
2- Is your customization page defined as one of woocommerce pages?
3- Does the product you are trying to customize exists and is published in your shop?
4- Are you accessing this page from one of the product designer buttons?
Please note that the Build-a-mailer is a design tool, submitting your designed mailer will not place an order. Once you submit your design your sales rep will contact you directly.
Also, note that our minimum order for custom branded mailers is 25,000+