I did some testing, and it turns out that it wasn't related to having an additional <input> tag. The problem was that the number in the "WriteText" column needs to match the number of radio button options offered. I had three choices, and the WriteText field defaults to 2. When I changed it to 3, it worked perfectly. I couldn't find anything in the manual about this field, and all questions in the forum about "WriteText" pointed to "write as text," which is different.