WebPlus X6: E-Commerce Form Problem

While adding an e-commerce form to my site, I need the customer to give me some additional information. In the page titled "Extra Customer Information" there is a dropdown that lets you ask for the customer name, address etc. which I've used. Below that is a dropdown box that says "if you wish to ask the customer an extra question on the order page enter the text here". That box is greyed out and will not accept an input. What have I done wrong?

Bill_S